Organic light-emitting device and electronic apparatus including the same

ABSTRACT

Embodiments provide an organic light-emitting device that includes a first electrode, a second electrode facing the first electrode, and an interlayer between the first electrode and the second electrode and including an emission layer. The emission layer includes a first compound, a second compound, a third compound, and a fourth compound, the first compound is a hole transporting host, the second compound is an electron transporting host, the third compound is a Pt complex, and the fourth compound is an Ir complex containing a halogen group.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to and benefits of Korean Patent Application No. 10-2022-0059105 under 35 U.S.C. § 119, filed on May 13, 2022, in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference.

BACKGROUND 1. Technical Field

Embodiments relate to an organic light-emitting device and an electronic apparatus including the organic light-emitting device.

2. Description of the Related Art

From among light-emitting devices, organic light-emitting devices are self-emissive devices that, as compared with devices of the related art, have wide viewing angles, high contrast ratios, short response times, and excellent characteristics in terms of luminance, driving voltage, and response speed.

As an example, an organic light-emitting device may have a structure in which a first electrode is arranged on a substrate, and a hole transport region, an emission layer, an electron transport region, and a second electrode are sequentially formed on the first electrode. Holes provided from the first electrode may move toward the emission layer through the hole transport region, and electrons provided from the second electrode may move toward the emission layer through the electron transport region. Carriers, such as the holes and electrons, may recombine in an emission layer region to produce excitons. These excitons transition from an excited state to the ground state to thereby generate light.

Fluorescent and phosphorescent materials have been used in organic light-emitting devices, but only fluorescent materials have been used for blue light-emitting devices. Because fluorescent materials have a theoretical quantum efficiency of 25%, and phosphorescent/thermally activated delayed fluorescence (TADF) materials can have a theoretical quantum efficiency of up to 100%, research has been conducted to develop blue phosphorescent devices having excellent efficiency and lifespan.

It is to be understood that this background of the technology section is, in part, intended to provide useful background for understanding the technology. However, this background of the technology section may also include ideas, concepts, or recognitions that were not part of what was known or appreciated by those skilled in the pertinent art prior to a corresponding effective filing date of the subject matter disclosed herein.

SUMMARY

Embodiments include a blue phosphorescent or thermally activated delayed fluorescence light-emitting device having low driving voltage, high color purity, excellent emission efficiency, and long lifespan.

Additional aspects will be set forth in part in the description, which follows and, in part, will be apparent from the description, or may be learned by practice of the embodiments of the disclosure.

According to embodiments, an organic light-emitting device may include a first electrode, a second electrode facing the first electrode, and an interlayer between the first electrode and the second electrode and including an emission layer,

wherein the emission layer may include a first compound, a second compound, a third compound, and a fourth compound, the first compound may be a hole transporting host, the second compound may be an electron transporting host, the third compound may be a platinum (Pt) complex, and the fourth compound may be an iridium (Ir) complex including a halogen group.

In an embodiment, the third compound may be represented by Formula 3:

In Formula 3,

-   -   CY₁ to CY₄ may each independently be a C₅-C₃₀ carbocyclic group         or a C₁-C₃₀ heterocyclic group,     -   L₁ to L₃ may each independently be a single bond, a double bond,         a substituted or unsubstituted C₆-C₃₀ arylene group, a         substituted or unsubstituted C₁-C₃₀ heteroarylene group, *—O—*′,         *—S—*′, *—C(═O)—*′, *—S(═O)—*′, *—C(Q₁)(Q₂)-*′,         *—C(Q₁)=C(Q₂)-*′, *—C(Q₁)=*′, *—Si(Q₁)(Q₂)-*′, *—B(Q₁)-*′,         *—N(Q₁)-*′, or *—P(Q₁)-*′,     -   T₁ to T₄ may each independently be a chemical bond, *—O—*′,         *—S—*′, *—B(Q₃)-*′, *—N(Q₃)-*′, *—P(Q₃)-*′, *—C(Q₃)(Q₄)-*,         *—Si(Q₃)(Q₄)-*′, *—Ge(Q₃)(Q₄)-*′, *—C(═O)—*′, or *—C(═S)—*′,     -   R₁ to R₄ may each independently be deuterium, —F, —Cl, —Br, —I,         a hydroxyl group, a cyano group, a nitro group, an amino group,         an amidino group, a hydrazine group, a hydrazone group, a         carboxylic acid group or a salt thereof, a sulfonic acid group         or a salt thereof, a phosphoric acid group or a salt thereof, a         substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted         or unsubstituted C₂-C₆₀ alkenyl group, a substituted or         unsubstituted C₂-C₆₀ alkynyl group, a substituted or         unsubstituted C₁-C₆₀ alkoxy group, a substituted or         unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or         unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or         unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted         C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀         arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl         group, a substituted or unsubstituted monovalent non-aromatic         condensed polycyclic group, a substituted or unsubstituted         monovalent non-aromatic condensed heteropolycyclic group,         —C(Q₅)(Q₆)(Q₇), —Si(Q₅)(Q₆)(Q₇), —B(Q₅)(Q₆), —N(Q₅)(Q₆),         —P(Q₅)(Q₆), —C(═O)(Q₅), —S(═O)(Q₅), —S(═O)₂(Q₅), —P(═O)(Q₅)(Q₆),         or —P(═S)(Q₅)(Q₆),     -   neighboring groups among R₁ to R₄ and L₁ to L₃ may optionally be         bonded to each other to form a substituted or unsubstituted         C₅-C₆₀ carbocyclic group or a substituted or unsubstituted         C₁-C₆₀ heterocyclic group,     -   a1 to a3 may each independently be an integer from 0 to 3,     -   b1 to b4 may each independently be an integer from 0 to 10,     -   at least one of substituents of the substituted C₆-C₃₀ arylene         group, the substituted C₁-C₃₀ heteroarylene group, the         substituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀ alkenyl         group, the substituted C₂-C₆₀ alkynyl group, the substituted         C₁-C₆₀ alkoxy group, the substituted C₃-C₁₀ cycloalkyl group,         the substituted C₁-C₁₀ heterocycloalkyl group, the substituted         C₃-C₁₀ cycloalkenyl group, the substituted C₁-C₁₀         heterocycloalkenyl group, the substituted C₆-C₆₀ aryl group, the         substituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀         arylthio group, the substituted C₁-C₆₀ heteroaryl group, the         substituted monovalent non-aromatic condensed polycyclic group,         the substituted monovalent non-aromatic condensed         heteropolycyclic group, the substituted C₅-C₆₀ carbocyclic         group, and the substituted C₁-C₆₀ heterocyclic group may be:     -   deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amidino group, a hydrazino group, a hydrazono         group, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀         alkynyl group, or a C₁-C₆₀ alkoxy group;     -   a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl         group, or a C₁-C₆₀ alkoxy group, each substituted with         deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amidino group, a hydrazino group, a hydrazono         group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl         group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl         group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀         arylthio group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀         heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a monovalent         non-aromatic condensed polycyclic group, a monovalent         non-aromatic condensed heteropolycyclic group,         —Si(Q₁₁)(Q₁₂)(Q₁₃), —N(Q₁₁)(Q₁₂), —B(Q₁₁)(Q₁₂), —C(═O)(Q₁₁),         —S(═O)₂(Q₁₁), —P(═O)(Q₁₁)(Q₁₂), or any combination thereof;     -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio         group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group,         a C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic         condensed polycyclic group, or a monovalent non-aromatic         condensed heteropolycyclic group;     -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio         group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group,         a C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic         condensed polycyclic group, or a monovalent non-aromatic         condensed heteropolycyclic group, each substituted with         deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amidino group, a hydrazino group, a hydrazono         group, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀         alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group,         a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a         C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀         aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl         group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio         group, a monovalent non-aromatic condensed polycyclic group, a         monovalent non-aromatic condensed heteropolycyclic group,         —Si(Q₂₁)(Q₂₂)(Q₂₃), —N(Q₂₁)(Q₂₂), —B(Q₂₁)(Q₂₂), —C(═O)(Q₂₁),         —S(═O)₂(Q₂₁), —P(═O)(Q₂₁)(Q₂₂), or any combination thereof; or     -   —Si(Q₃₁)(Q₃₂)(Q₃₃), —N(Q₃₁)(Q₃₂), —B(Q₃₁)(Q₃₂), —C(═O)(Q₃₁),         —S(═O)₂(Q₃₁), or —P(═O)(Q₃₁)(Q₃₂), and     -   Q₁ to Q₃, Q₁₁ to Q₁₃, Q₂₁ to Q₂₃, and Q₃₁ to Q₃₃ may each         independently be hydrogen, deuterium, —F, —Cl, —Br, —I, a         hydroxyl group, a cyano group, a nitro group, an amidino group,         a hydrazino group, a hydrazono group, a C₁-C₆₀ alkyl group, a         C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy         group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl         group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl         group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀         arylthio group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀         heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a monovalent         non-aromatic condensed polycyclic group, a monovalent         non-aromatic condensed heteropolycyclic group, a biphenyl group,         or a terphenyl group.

In an embodiment, the third compound may be represented by Formula 3A, which is explained below.

In an embodiment, the third compound may include one of Compounds 3-1 to 3-6, which are explained below.

In an embodiment, the halogen group of the fourth compound may be directly bonded to an Ir atom.

In an embodiment, the fourth compound may be represented by Formula 4:

In Formula 4,

-   -   CY₅ and CY₆ may each independently be a C₅-C₃₀ carbocyclic group         or a C₁-C₃₀ heterocyclic group,     -   each L₅ may independently be a single bond, a double bond, a         substituted or unsubstituted C₆-C₃₀ arylene group, a substituted         or unsubstituted C₁-C₃₀ heteroarylene group, *—O—*′, *—S—*′,         *—C(═O)—*′, *—S(═O)—*′, *—C(Q₁)(Q₂)-*′, *—C(Q₁)=C(Q₂)-*′,         *—C(Q₁)=*′, *—Si(Q₁)(Q₂)-*′, *—B(Q₁)-*′, *—N(Q₁)-*′, or         *—P(Q₁)-*′,     -   T₇ may be a chemical bond, *—O—*′, *—S—*′, *—B(Q₃)-*′,         *—N(Q₃)-*′, *—P(Q₃)-*′, *—C(Q₃)(Q₄)-*, *—Si(Q₃)(Q₄)-*′,         *—Ge(Q₃)(Q₄)-*′, *—C(═O)—*′, or *—C(═S)—*′,     -   R₅ and R₆ may each independently be deuterium, —F, —Cl, —Br, —I,         a hydroxyl group, a cyano group, a nitro group, an amino group,         an amidino group, a hydrazine group, a hydrazone group, a         carboxylic acid group or a salt thereof, a sulfonic acid group         or a salt thereof, a phosphoric acid group or a salt thereof, a         substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted         or unsubstituted C₂-C₆₀ alkenyl group, a substituted or         unsubstituted C₂-C₆₀ alkynyl group, a substituted or         unsubstituted C₁-C₆₀ alkoxy group, a substituted or         unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or         unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or         unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted         C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀         arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl         group, a substituted or unsubstituted monovalent non-aromatic         condensed polycyclic group, a substituted or unsubstituted         monovalent non-aromatic condensed heteropolycyclic group,         —C(Q₅)(Q₆)(Q₇), —Si(Q₅)(Q₆)(Q₇), —B(Q₅)(Q₆), —N(Q₅)(Q₆),         —P(Q₅)(Q₆), —C(═O)(Q₅), —S(═O)(Q₅), —S(═O)₂(Q₅), —P(═O)(Q₅)(Q₆),         or —P(═S)(Q₅)(Q₆),     -   Y₇ may be a substituted or unsubstituted C₁-C₆₀ alkyl group, a         substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted         or unsubstituted C₂-C₆₀ alkynyl group, a substituted or         unsubstituted C₁-C₆₀ alkoxy group, a substituted or         unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or         unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or         unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted         C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀         arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl         group, a substituted or unsubstituted monovalent non-aromatic         condensed polycyclic group, a substituted or unsubstituted         monovalent non-aromatic condensed heteropolycyclic group,         —C(Q₈)(Q₉)(Q₁₀), —Si(Q₈)(Q₉)(Q₁₀), —B(Q₈)(Q₉), —N(Q₈)(Q₉),         —P(Q₈)(Q₉), —C(═O)(Q₈), —S(═O)(Q₈), —S(═O)₂(Q₈), —P(═O)(Q₈)(Q₉),         or —P(═S)(Q₈)(Q₉),     -   Q₁ to Q₁ o may each independently be hydrogen, deuterium, —F,         —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amidino group, a hydrazino group, a hydrazono group, a C₁-C₆₀         alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a         C₁-C₆ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀         heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀         heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy         group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a         C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a         monovalent non-aromatic condensed polycyclic group, a monovalent         non-aromatic condensed heteropolycyclic group, a biphenyl group,         or a terphenyl group,     -   a5 may be an integer from 0 to 3,     -   b5 and b6 may each independently be an integer from 0 to 10,     -   c3 may be 0, 1, 2, or 3,     -   d3 may be 1, 2, or 3, and     -   X may be F, Cl, or I.     -   In an embodiment, in Formula 4,     -   CY₅ and CY₆ may each independently be a benzene group, a         naphthalene group, an anthracene group, a phenanthrene group, a         triphenylene group, a pyrene group, a chrysene group, a         cyclopentadiene group, a 1,2,3,4-tetrahydronaphthalene group, a         carbene group, a thiophene group, a furan group, a selenophene         group, an indole group, a benzoborole group, a benzophosphole         group, an indene group, a benzosilole group, a benzogermole         group, a benzothiophene group, a benzoselenophene group, a         benzofuran group, a carbazole group, a dibenzoborole group, a         dibenzophosphole group, a fluorene group, a dibenzosilole group,         a dibenzogermole group, a dibenzothiophene group, a         dibenzoselenophene group, a dibenzofuran group, a         dibenzothiophene 5-oxide group, a 9H-fluorene-9-one group, a         dibenzothiophene 5,5-dioxide group, an azaindole group, an         azabenzoborole group, an azabenzophosphole group, an azaindene         group, an azabenzosilole group, an azabenzogermole group, an         azabenzothiophene group, an azabenzoselenophene group, an         azabenzofuran group, an azacarbazole group, an azadibenzoborole         group, an azadibenzophosphole group, an azafluorene group, an         azadibenzosilole group, an azadibenzogermole group, an         azadibenzothiophene group, an azadibenzoselenophene group, an         azadibenzofuran group, an azadibenzothiophene 5-oxide group, an         aza-9H-fluorene-9-one group, an azadibenzothiophene 5,5-dioxide         group, a pyridine group, a pyrimidine group, a pyrazine group, a         pyridazine group, a triazine group, a quinoline group, an         isoquinoline group, a quinoxaline group, a quinazoline group, a         phenanthroline group, a pyrrole group, a pyrazole group, an         imidazole group, a triazole group, an oxazole group, an         isooxazole group, a thiazole group, an isothiazole group, an         oxadiazole group, a thiadiazole group, a benzopyrazole group, a         benzimidazole group, a benzoxazole group, a benzothiazole group,         a benzoxadiazole group, a benzothiadiazole group, a         5,6,7,8-tetrahydroisoquinoline group, or a         5,6,7,8-tetrahydroquinoline group,     -   T₇ may be a chemical bond, *—O—*′, or *—S—*′,     -   L₅ may be a single bond, and     -   Y₇ may be a substituted or unsubstituted C₂-C₂₀ alkenyl group, a         substituted or unsubstituted C₆-C₂₀ aryl group, a substituted or         unsubstituted C₂-C₂₀ heteroaryl group, a substituted or         unsubstituted monovalent non-aromatic condensed polycyclic         group, or a substituted or unsubstituted monovalent non-aromatic         condensed heteropolycyclic group.

In an embodiment, the fourth compound may include one of Compounds 4-1 to 4-30, which are explained below.

In an embodiment, the organic light-emitting device may further include a fifth compound. The fifth compound may be a fluorescent dopant or a delayed fluorescence dopant.

In an embodiment, the fifth compound may include a compound represented by Formula 5, a compound represented by Formula 6, a compound represented by Formula 7, or any combination thereof, wherein Formulae 5 to 7 are explained below.

In an embodiment, the compound represented by Formula 5 may include at least one of Compounds 5-1 to 5-4, which are explained below, the compound represented by Formula 6 may include at least one of Compounds 6-1 to 6-6, which are explained below, and the compound represented by Formula 7 may include at least one of Compounds 7-1 and 7-2, which are explained below.

In an embodiment, an emission peak wavelength of an emission spectrum of the third compound may be greater than an emission peak wavelength of an emission spectrum of the fourth compound.

In an embodiment, an emission peak wavelength of the emission layer may be in a range of about 430 nm to about 480 nm.

In an embodiment, a ratio of emission components emitted from the third compound to total emission components emitted from the emission layer may be greater than or equal to about 80%.

In an embodiment, an emission peak wavelength of an emission spectrum of the fifth compound may be greater than an emission peak wavelength of an emission spectrum of the fourth compound.

In an embodiment, an emission peak wavelength of the emission layer may be in a range of about 430 nm to about 480 nm.

In an embodiment, a ratio of emission components emitted from the fifth compound to total emission components emitted from the emission layer may be greater than or equal to about 80%.

According to embodiments, an electronic apparatus may include the organic light-emitting device.

In an embodiment, the electronic apparatus may further include a thin-film transistor, wherein the thin-film transistor may include a source electrode, a drain electrode, an active layer, and a gate electrode, and the first electrode of the organic light-emitting device may be electrically connected to the source electrode or the drain electrode.

In an embodiment, the electronic apparatus may further include a color filter, a color conversion layer, a touch screen layer, a polarizing layer, or any combination thereof

It is to be understood that the embodiments above are described in a generic and explanatory sense only and not for the purpose of limitation, and the disclosure is not limited to the embodiments described above.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects and features of the disclosure will be more apparent by describing in detail embodiments thereof with reference to the accompanying drawings, in which:

FIG. 1 is a schematic cross-sectional view of an organic light-emitting device according to an embodiment;

FIG. 2 is a schematic cross-sectional view of a structure of an electronic apparatus according to an embodiment; and

FIG. 3 is a schematic cross-sectional view of a structure of an electronic apparatus according to another embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments are shown. This disclosure may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

In the drawings, the sizes, thicknesses, ratios, and dimensions of the elements may be exaggerated for ease of description and for clarity. Like numbers refer to like elements throughout.

In the description, it will be understood that when an element (or region, layer, part, etc.) is referred to as being “on”, “connected to”, or “coupled to” another element, it can be directly on, connected to, or coupled to the other element, or one or more intervening elements may be present therebetween. In a similar sense, when an element (or region, layer, part, etc.) is described as “covering” another element, it can directly cover the other element, or one or more intervening elements may be present therebetween.

In the description, when an element is “directly on,” “directly connected to,” or “directly coupled to” another element, there are no intervening elements present. For example, “directly on” may mean that two layers or two elements are disposed without an additional element such as an adhesion element therebetween.

AAs used herein, the expressions used in the singular such as “a,” “an,” and “the,” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. For example, “A and/or B” may be understood to mean “A, B, or A and B.” The terms “and” and “or” may be used in the conjunctive or disjunctive sense and may be understood to be equivalent to “and/or”.

In the specification and the claims, the term “at least one of” is intended to include the meaning of “at least one selected from the group consisting of” for the purpose of its meaning and interpretation. For example, “at least one of A, B, and C” may be understood to mean A only, B only, C only, or any combination of two or more of A, B, and C, such as ABC, ACC, BC, or CC.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element.

Thus, a first element could be termed a second element without departing from the teachings of the disclosure. Similarly, a second element could be termed a first element, without departing from the scope of the disclosure.

The spatially relative terms “below”, “beneath”, “lower”, “above”, “upper”, or the like, may be used herein for ease of description to describe the relations between one element or component and another element or component as illustrated in the drawings. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the drawings. For example, in the case where a device illustrated in the drawing is turned over, the device positioned “below” or “beneath” another device may be placed “above” another device. Accordingly, the illustrative term “below” may include both the lower and upper positions. The device may also be oriented in other directions and thus the spatially relative terms may be interpreted differently depending on the orientations.

The terms “about” or “approximately” as used herein is inclusive of the stated value and means within an acceptable range of deviation for the recited value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the recited quantity (i.e., the limitations of the measurement system). For example, “about” may mean within one or more standard deviations, or within +20%, 10%, or ±5% of the stated value.

It should be understood that the terms “comprises,” “comprising,” “includes,” “including,” “have,” “having,” “contains,” “containing,” and the like are intended to specify the presence of stated features, integers, steps, operations, elements, components, or combinations thereof in the disclosure, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless otherwise defined or implied herein, all terms (including technical and scientific terms) used have the same meaning as commonly understood by those skilled in the art to which this disclosure pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and should not be interpreted in an ideal or excessively formal sense unless clearly defined in the specification.

The expression “(interlayer) includes a compound represented by Formula 1” as used herein may mean that the interlayer may include one kind of compound represented by Formula 1 or two or more different kinds of compounds, each independently represented by Formula 1.

In the description, an organic light-emitting device according to embodiments and an electronic apparatus including the same are described in detail.

[Organic Light-Emitting Device]

FIG. 1 is a schematic cross-sectional view of an organic light-emitting device 10 according to an embodiment. The organic light-emitting device 10 includes a first electrode 110, an interlayer 130, and a second electrode 150.

Hereinafter, a structure of the organic light-emitting device 10 according to an embodiment and a method of manufacturing the organic light-emitting device 10 will be described in connection with FIG. 1 .

[First Electrode 110]

In FIG. 1 , a substrate may be further included under the first electrode 110 or above the second electrode 150. In an embodiment, the substrate may be a glass substrate or a plastic substrate. In an embodiment, the substrate may be a flexible substrate, and may include plastics with excellent heat resistance and durability, such as polyimide, polyethylene terephthalate (PET), polycarbonate, polyethylene naphthalate, polyarylate (PAR), polyetherimide, or any combination thereof.

The first electrode 110 may be formed by, for example, depositing or sputtering a material for forming the first electrode 110 on the substrate. When the first electrode 110 is an anode, a material for forming the first electrode 110 may be a high work function material that facilitates the injection of holes.

The first electrode 110 may be a reflective electrode, a semi-transmissive electrode, or a transmissive electrode. When the first electrode 110 is a transmissive electrode, a material for forming the first electrode 110 may include indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO₂), zinc oxide (ZnO), or any combination thereof. In an embodiment, when the first electrode 110 is a semi-transmissive electrode or a reflective electrode, a material for forming the first electrode 110 may include magnesium (Mg), silver (Ag), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), magnesium-silver (Mg—Ag), or any combination thereof.

The first electrode 110 may have a structure consisting of a single layer, or a structure including multiple layers. In an embodiment, the first electrode 110 may have a three-layered structure of ITO/Ag/ITO.

[Interlayer 130]

The interlayer 130 is located on the first electrode 110. The interlayer may include an emission layer.

The interlayer 130 may further include a hole transport region located between the first electrode 110 and the emission layer, and an electron transport region located between the emission layer and the second electrode 150.

The interlayer 130 may include an organic compound, a metal-containing compound (for example, an organometallic compound), an inorganic material such as a metal or a quantum dot, or any combination thereof.

In an embodiment, the interlayer 130 may include two or more emitting units stacked between the first electrode 110 and the second electrode 150, and at least one charge generation layer located between the two or more emitting units. When the interlayer 130 includes the two or more emitting units and the at least one charge generation layer as described above, the organic light-emitting device 10 may be a tandem organic light-emitting device.

[Hole Transport Region in Interlayer 130]

The hole transport region may have a structure consisting of a layer consisting of a single material, a structure consisting of a layer including different materials, or a structure including multiple layers including different materials.

The hole transport region may include a hole injection layer, a hole transport layer, an emission auxiliary layer, an electron blocking layer, or any combination thereof.

In embodiments, the hole transport region may have a multilayer structure including a hole injection layer/hole transport layer structure, a hole injection layer/hole transport layer/emission auxiliary layer structure, a hole injection layer/emission auxiliary layer structure, a hole transport layer/emission auxiliary layer structure, or a hole injection layer/hole transport layer/electron blocking layer structure, wherein the layers of each structure may be stacked from the first electrode 110 in its respective stated order, but embodiments are not limited thereto.

The hole transport region may include a compound represented by Formula 201, a compound represented by Formula 202, or any combination thereof:

In Formulae 201 and 202,

-   -   L₂₀₁ to L₂₀₄ may each independently be a C₃-C₆₀ carbocyclic         group that is unsubstituted or substituted with at least one         R_(a) or a C₁-C₆₀ heterocyclic group that is unsubstituted or         substituted with at least one R_(a),     -   L₂₀₅ may be *—O—*′, *—S—*′, *—N(Q₂₀₁)-*′, a C₁-C₂₀ alkylene         group that is unsubstituted or substituted with at least one         R_(a), a C₂-C₂₀ alkenylene group that is unsubstituted or         substituted with at least one R_(a), a C₃-C₆₀ carbocyclic group         that is unsubstituted or substituted with at least one R_(a), or         a C₁-C₆₀ heterocyclic group that is unsubstituted or substituted         with at least one R_(a),     -   xa1 to xa4 may each independently be an integer from 0 to 5,     -   xa5 may be an integer from 1 to 10,     -   R₂₀₁ to R₂₀₄ and Q₂₀₁ may each independently be a C₃-C₆₀         carbocyclic group that is unsubstituted or substituted with at         least one R_(a) or a C₁-C₆₀ heterocyclic group that is         unsubstituted or substituted with at least one R_(a),     -   R₂₀₁ and R₂₀₂ may optionally be linked to each other via a         single bond, a C₁-C₅ alkylene group that is unsubstituted or         substituted with at least one R_(a), or a C₂-C₅ alkenylene group         that is unsubstituted or substituted with at least one R_(a) to         form a C₈-C₆₀ polycyclic group (for example, a carbazole group)         that is unsubstituted or substituted with at least one R_(a)         (for example, see Compound HT16),     -   R₂₀₃ and R₂₀₄ may optionally be linked to each other via a         single bond, a C₁-C₅ alkylene group that is unsubstituted or         substituted with at least one R_(a), or a C₂-C₅ alkenylene group         that is unsubstituted or substituted with at least one R_(a) to         form a C₈-C₆₀ polycyclic group that is unsubstituted or         substituted with at least one R_(a), and     -   na1 may be an integer from 1 to 4.     -   R_(a) may be:     -   deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, or         a nitro group;

a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, or a C₁-C₆₀ alkoxy group, each unsubstituted or substituted with deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, a C₃-C₆₀ carbocyclic group, a C₁-C₆₀ heterocyclic group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ aryl alkyl group, a C₂-C₆₀ heteroaryl alkyl group, —Si(Q₁₁)(Q₁₂)(Q₁₃), —N(Q₁₁)(Q₁₂), —B(Q₁₁)(Q₁₂), —C(═O)(Q₁₁), —S(═O)₂(Q₁₁), —P(═O)(Q₁₁)(Q₁₂), or any combination thereof;

-   -   a C₃-C₆₀ carbocyclic group, a C₁-C₆₀ heterocyclic group, a         C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ aryl         alkyl group, or a C₂-C₆₀ heteroaryl alkyl group, each         unsubstituted or substituted with deuterium, —F, —Cl, —Br, —I, a         hydroxyl group, a cyano group, a nitro group, a C₁-C₆₀ alkyl         group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀         alkoxy group, a C₃-C₆₀ carbocyclic group, a C₁-C₆₀ heterocyclic         group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀         aryl alkyl group, a C₂-C₆₀ heteroaryl alkyl group,         —Si(Q₂₁)(Q₂₂)(Q₂₃), —N(Q₂₁)(Q₂₂), —B(Q₂₁)(Q₂₂), —C(═O)(Q₂₁),         —S(═O)₂(Q₂₁), —P(═O)(Q₂₁)(Q₂₂), or any combination thereof; or     -   —Si(Q₃₁)(Q₃₂)(Q₃₃), —N(Q₃₁)(Q₃₂), —B(Q₃₁)(Q₃₂), —C(═O)(Q₃₁),         —S(═O)₂(Q₃₁), or —P(═O)(Q₃₁)(Q₃₂), and     -   Q₁ to Q₃, Q₁₁ to Q₁₃, Q₂₁ to Q₂₃, and Q₃₁ to Q₃₃ may each         independently be: hydrogen; deuterium; —F; —Cl; —Br; —I; a         hydroxyl group; a cyano group; a nitro group; a C₁-C₆₀ alkyl         group; a C₂-C₆₀ alkenyl group; a C₂-C₆₀ alkynyl group; a C₁-C₆₀         alkoxy group; or a C₃-C₆₀ carbocyclic group, a C₁-C₆₀         heterocyclic group, a C₇-C₆₀ aryl alkyl group, or a C₂-C₆₀         heteroaryl alkyl group, each unsubstituted or substituted with         deuterium, —F, a cyano group, a C₁-C₆₀ alkyl group, a C₁-C₆₀         alkoxy group, a phenyl group, a biphenyl group, or any         combination thereof.

In an embodiment, the compound represented by Formula 201 and the compound represented by Formula 202 may each independently include at least one of groups represented by Formulae CY201 to CY217:

In Formulae CY201 to CY217, R_(10b) and R_(10c) may each independently be the same as described in connection with R_(a), ring CY₂₀₁ to ring CY₂₀₄ may each independently be a C₃-C₂₀ carbocyclic group or a C₁-C₂₀ heterocyclic group, and at least one hydrogen in Formulae CY201 to CY217 may be unsubstituted or substituted with R_(a) as described herein.

In an embodiment, in Formulae CY201 to CY217, ring CY₂₀₁ to ring CY₂₀₄ may each independently be a benzene group, a naphthalene group, a phenanthrene group, or an anthracene group.

In an embodiment, the compound represented by Formula 201 and the compound represented by Formula 202 may each independently include at least one of groups represented by Formulae CY201 to CY203.

In an embodiment, the compound represented by Formula 201 may include at least one of the groups represented by Formulae CY201 to CY203 and at least one of groups represented by Formulae CY204 to CY217.

In an embodiment, in Formula 201, xa1 may be 1, R₂₀₁ may be a group represented by one of Formulae CY201 to CY203, xa2 may be 0, and R₂₀₂ may be a group represented by one of Formulae CY204 to CY207.

In an embodiment, the compound represented by Formula 201 and the compound represented by Formula 202 may each not include groups represented by Formulae CY201 to CY203.

In an embodiment, the compound represented by Formula 201 and the compound represented by Formulae 202 may each not include groups represented by Formulae CY201 to CY203, and may each independently include at least one of groups represented by Formulae CY204 to CY217.

In an embodiment, the compound represented by Formula 201 and the compound represented by Formula 202 may each not include groups represented by Formulae CY201 to CY217.

In an embodiment, the hole transport region may include one of Compounds HT1 to HT47, m-MTDATA, TDATA, 2-TNATA, NPB(NPD), p-NPB, TPD, Spiro-TPD, Spiro-NPB, methylated NPB, TAPC, HMTPD, 4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA), polyaniline/dodecylbenzenesulfonic acid (PANI/DBSA), poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS), polyaniline/camphor sulfonic acid (PANI/CSA), polyaniline/poly(4-styrenesulfonate) (PANI/PSS), or any combination thereof:

A thickness of the hole transport region may be in a range of about 50 Å to about 10,000 Å. For example, the thickness of the hole transport region may be in a range of about 100 Å to about 4,000 Å. When the hole transport region includes a hole injection layer, a hole transport layer, or any combination thereof, a thickness of the hole injection layer may be in a range of about 100 Å to about 9,000 Å, and a thickness of the hole transport layer may be in a range of about 50 Å to about 2,000 Å. For example, the thickness of the hole injection layer may be in a range of about 100 Å to about 1,000 Å. For example, the thickness of the hole transport layer may be in a range of about 100 Å to about 1,500 Å. When the thicknesses of the hole transport region, the hole injection layer and the hole transport layer are within these ranges, satisfactory hole-transporting characteristics may be obtained without a substantial increase in driving voltage.

The emission auxiliary layer may increase light-emission efficiency by compensating for an optical resonance distance according to a wavelength of light emitted by an emission layer, and the electron blocking layer may block the leakage of electrons from an emission layer to a hole transport region. Materials that may be included in the hole transport region may be included in the emission auxiliary layer and the electron blocking layer.

[p-Dopant]

The hole transport region may further include, in addition to these materials, a charge-generation material for the improvement of conductive properties. The charge-generation material may be uniformly or non-uniformly dispersed in the hole transport region (for example, in the form of a single layer consisting of a charge-generation material).

The charge-generation material may be, for example, a p-dopant.

In an embodiment, a lowest unoccupied molecular orbital (LUMO) energy level of the p-dopant may be equal to or less than about −3.5 eV.

In an embodiment, the p-dopant may include a quinone derivative, a cyano group-containing compound, a compound including element EL1 and element EL2, or any combination thereof.

Examples of the quinone derivative may include TCNQ, F4-TCNQ, and the like.

Examples of the cyano group-containing compound may include HAT-CN, a compound represented by Formula 221, and the like:

In Formula 221,

-   -   R₂₂₁ to R₂₂₃ may each independently be a C₃-C₆₀ carbocyclic         group that is unsubstituted or substituted with at least one         R_(a) or a C₁-C₆₀ heterocyclic group that is unsubstituted or         substituted with at least one R_(a), and     -   at least one of R₂₂₁ to R₂₂₃ may each independently be a C₃-C₆₀         carbocyclic group or a C₁-C₆₀ heterocyclic group, each         substituted with: a cyano group; —F; —Cl; —Br; -A; a C₁-C₂₀         alkyl group that is substituted with a cyano group, —F, —Cl,         —Br, —I, or any combination thereof; or any combination thereof.

In the compound including element EL1 and element EL2, element EL1 may be a metal, a metalloid, or a combination thereof, and element EL2 may be a non-metal, a metalloid, or a combination thereof.

Examples of the metal may include: an alkali metal (for example, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), etc.); an alkaline earth metal (for example, beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), etc.); a transition metal (for example, titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), etc.); a post-transition metal (for example, zinc (Zn), indium (In), tin (Sn), etc.); and a lanthanide metal (for example, lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), etc.).

Examples of the metalloid may include silicon (Si), antimony (Sb), and tellurium (Te).

Examples of the non-metal may include oxygen (O) and a halogen (for example, F, Cl, Br, I, etc.).

In an embodiment, examples of the compound including element EL1 and element EL2 may include a metal oxide, a metal halide (for example, a metal fluoride, a metal chloride, a metal bromide, or a metal iodide), a metalloid halide (for example, a metalloid fluoride, a metalloid chloride, a metalloid bromide, or a metalloid iodide), a metal telluride, or any combination thereof.

Examples of the metal oxide may include a tungsten oxide (for example, WO, W₂O₃, WO₂, WO₃, W₂O₅, etc.), a vanadium oxide (for example, VO, V₂O₃, VO₂, V₂O₅, etc.), a molybdenum oxide (MoO, Mo₂O₃, MoO₂, MoO₃, Mo₂O₅, etc.), and a rhenium oxide (for example, ReO₃, etc.).

Examples of the metal halide may include an alkali metal halide, an alkaline earth metal halide, a transition metal halide, a post-transition metal halide, and a lanthanide metal halide.

Examples of the alkali metal halide may include LiF, NaF, KF, RbF, CsF, LiCl, NaCl, KCl, RbCl, CsCl, LiBr, NaBr, KBr, RbBr, CsBr, LiI, NaI, KI, RbI, and CsI.

Examples of the alkaline earth metal halide may include BeF₂, MgF₂, CaF₂, SrF₂, BaF₂, BeCl₂, MgCl₂, CaCl₂), SrCl₂, BaCl₂, BeBr₂, MgBr₂, CaBr₂, SrBr₂, BaBr₂, BeI₂, MgI₂, CaI₂, SrI₂, and Bal₂.

Examples of the transition metal halide may include a titanium halide (for example, TiF₄, TiCl₄, TiBr₄, TiI₄, etc.), a zirconium halide (for example, ZrF₄, ZrCl₄, ZrBr₄, ZrI₄, etc.), a hafnium halide (for example, HfF₄, HfCl₄, HfBr₄, HfI₄, etc.), a vanadium halide (for example, VF₃, VCI₃, VBr₃, VI₃, etc.), a niobium halide (for example, NbF₃, NbCl₃, NbBr₃, NbI₃, etc.), a tantalum halide (for example, TaF₃, TaCl₃, TaBr₃, TaI₃, etc.), a chromium halide (for example, CrF₃, CrCl₃, CrBr₃, CrI₃, etc.), a molybdenum halide (for example, MoF₃, MoCl₃, MoBr₃, MoI₃, etc.), a tungsten halide (for example, WF₃, WCl₃, WBr₃, WI₃, etc.), a manganese halide (for example, MnF₂, MnCl₂, MnBr₂, MnI₂, etc.), a technetium halide (for example, TcF₂, TcCl₂, TcBr₂, TcI₂, etc.), a rhenium halide (for example, ReF₂, ReCl₂, ReBr₂, ReI₂, etc.), an iron halide (for example, FeF₂, FeCl₂, FeBr₂, FeI₂, etc.), a ruthenium halide (for example, RuF₂, RuCl₂, RuBr₂, RuI₂, etc.), an osmium halide (for example, OsF₂, OsCl₂, OsBr₂, OsI₂, etc.), a cobalt halide (for example, CoF₂, CoCl₂, CoBr₂, COI₂, etc.), a rhodium halide (for example, RhF₂, RhCl₂, RhBr₂, RhI₂, etc.), an iridium halide (for example, IrF₂, IrCl₂, IrBr₂, IrI₂, etc.), a nickel halide (for example, NiF₂, NiCl₂, NiBr₂, NiI₂, etc.), a palladium halide (for example, PdF₂, PdCl₂, PdBr₂, PdI₂, etc.), a platinum halide (for example, PtF₂, PtCl₂, PtBr₂, PtI₂, etc.), a copper halide (for example, CuF, CuCl, CuBr, CuI, etc.), a silver halide (for example, AgF, AgCl, AgBr, AgI, etc.), and a gold halide (for example, AuF, AuCl, AuBr, AuI, etc.).

Examples of the post-transition metal halide may include a zinc halide (for example, ZnF₂, ZnCl₂, ZnBr₂, ZnI₂, etc.), an indium halide (for example, InI₃, etc.), and a tin halide (for example, SnI₂, etc.).

Examples of the lanthanide metal halide may include YbF, YbF₂, YbF₃, SmF₃, YbCl, YbCl₂, YbCl₃, SmCl₃, YbBr, YbBr₂, YbBr₃, SmBr₃, YbI, YbI₂, YbI₃, and SmI₃.

Examples of the metalloid halide may include an antimony halide (for example, SbCl₅, etc.).

Examples of the metal telluride may include an alkali metal telluride (for example, Li₂Te, Na₂Te, K₂Te, Rb₂Te, Cs₂Te, etc.), an alkaline earth metal telluride (for example, BeTe, MgTe, CaTe, SrTe, BaTe, etc.), a transition metal telluride (for example, TiTe₂, ZrTe₂, HfTe₂, V₂Te₃, Nb₂Te₃, Ta₂Te₃, Cr₂Te₃, Mo₂Te₃, W₂Te₃, MnTe, TcTe, ReTe, FeTe, RuTe, OsTe, CoTe, RhTe, IrTe, NiTe, PdTe, PtTe, Cu₂Te, CuTe, Ag₂Te, AgTe, Au₂Te, etc.), a post-transition metal telluride (for example, ZnTe, etc.), and a lanthanide metal telluride (for example, LaTe, CeTe, PrTe, NdTe, PmTe, EuTe, GdTe, TbTe, DyTe, HoTe, ErTe, TmTe, YbTe, LuTe, etc.).

[Emission Layer in Interlayer 130]

When the organic light-emitting device 10 is a full-color organic light-emitting device, the emission layer may be patterned into a red emission layer, a green emission layer, and/or a blue emission layer, according to a subpixel. In an embodiment, the emission layer may have a stacked structure of two or more layers of a red emission layer, a green emission layer, and a blue emission layer, in which the two or more layers may contact each other or may be separated from each other. In an embodiment, the emission layer may include two or more materials of a red light-emitting material, a green light-emitting material, and a blue light-emitting material, in which the two or more materials may be mixed with each other in a single layer to emit white light.

The emission layer may include a first compound, a second compound, a third compound, and a fourth compound. The first compound may be a hole transporting host, and the second compound may be an electron transporting host. The third compound may be a platinum (Pt) complex, and the fourth compound may be an iridium (Ir) complex containing a halogen group. The third compound may be a phosphorescent dopant, and the fourth compound may be a sensitizer.

A thickness of the emission layer may be in a range of about 100 Å to about 1,000 Å. For example, the thickness of the emission layer may be in a range of about 200 Å to about 600 Å. When the thickness of the emission layer is within these ranges, excellent light-emission characteristics may be obtained without a substantial increase in driving voltage.

[First Compound]

In an embodiment, the first compound may be a compound including at least one hole transporting moiety. In an embodiment, the hole transporting moiety may include a carbazole group, a dibenzofuran group, a dibenzothiophene group, a dibenzosilole group, or an amine group, but embodiments are not limited thereto.

In an embodiment, the first compound may include at least one moiety represented by one of Formulae 1-1 to 1-3:

In Formulae 1-1 to 1-3,

-   -   X₁₁ may be O, S, N(R₃₅), C(R₃₅)(R₃₆), or Si(R₃₅)(R₃₆),     -   R₃₅ and R₃₆ may each independently be a C₁-C₆₀ alkyl group, a         C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy         group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl         group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl         group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀         arylthio group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀         heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a monovalent         non-aromatic condensed polycyclic group, or a monovalent         non-aromatic condensed heteropolycyclic group,     -   CY₁₁ and CY₁₂ may each independently be a π electron-rich cyclic         group, and     -   , *′, and *″ may each indicate a binding site to a neighboring         atom.

The term “π electron-rich cyclic group” as used herein may be a carbocyclic or heterocyclic group that does not include *═N—*′ as a ring-forming moiety.

Examples of the “π electron-rich cyclic group” may include a benzene group, a heptalene group, an indene group, a naphthalene group, an azulene group, a heptalene group, an indacene group, an acenaphthylene group, a fluorene group, a spiro-bifluorene group, a benzofluorene group, a dibenzofluorene group, a phenalene group, a phenanthrene group, an anthracene group, a fluoranthene group, a triphenylene group, a pyrene group, a chrysene group, a naphthacene group, a picene group, a perylene group, a pentacene group, a hexacene group, a pentaphene group, a rubicene group, a coronene group, an ovalene group, a pyrrole group, a furan group, a thiophene group, an iso-indole group, an indole group, an indene group, a benzofuran group, a benzothiophene group, a benzosilole group, a naphthopyrrole group, a naphthofuran group, a naphthothiophene group, a naphthosilole group, a benzocarbazole group, a dibenzocarbazole group, a dibenzofuran group, a dibenzothiophene group, a dibenzothiophene sulfone group, a carbazole group, a dibenzosilole group, an indenocarbazole group, an indolocarbazole group, a benzofurocarbazole group, a benzothienocarbazole group, a benzosilolocarbazole group, a triindolobenzene group, an acridine group, a dihydroacridine group, a benzonaphthofuran group, a benzonaphthothiophene group, a (indolo)phenanthrene group, a (benzofurano)phenanthrene group, or a (benzothieno)phenanthrene group, but embodiments are not limited thereto.

In an embodiment, in Formulae 1-1 to 1-3, CY₁₁ and CY₁₂ may each independently be a benzene group, a naphthalene group, a fluorene group, a carbazole group, a dibenzofuran group, a dibenzothiophene group, or a dibenzosilole group.

In an embodiment, the first compound may be a hole transporting host including at least one moiety represented by one of Formulae 1-1 to 1-3.

In an embodiment, the first compound may be a compound represented by one of Formulae 1-11 to 1-14:

In Formula 1-11,

-   -   CY₄₁ and CY₄₂ may each independently be a π electron-rich cyclic         group having 3 to 30 carbon atoms,     -   X₄₁ may be O, S, N-(L₄₁)_(a41)-(R₄₁)_(b41), C(R₄₁)(R₄₁), or         Si(R₄₁)(R₄₄), and     -   c41 and c42 may each independently be an integer from 0 to 3.

In Formulae 1-11 to 1-14,

-   -   L₄₁ to L₄₇ may each independently be a single bond, a         substituted or unsubstituted C₅-C₃₀ carbocyclic group, or a         substituted or unsubstituted C₁-C₃₀ heterocyclic group,     -   a41 to a47 may each independently be an integer from 1 to 10,     -   R₄₁ to R₄₇ may each independently be hydrogen, deuterium, —F,         —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amidino group, a hydrazine group, a hydrazone group, a         carboxylic acid group or a salt thereof, a sulfonic acid group         or a salt thereof, a phosphoric acid group or a salt thereof, a         substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted         or unsubstituted C₂-C₆₀ alkenyl group, a substituted or         unsubstituted C₂-C₆₀ alkynyl group, a substituted or         unsubstituted C₁-C₆₀ alkoxy group, a substituted or         unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or         unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or         unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted         C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀         arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl         group, a substituted or unsubstituted monovalent non-aromatic         condensed polycyclic group, a substituted or unsubstituted         monovalent non-aromatic condensed heteropolycyclic group,         —Si(Q₁)(Q₂)(Q₃), —N(Q₁)(Q₂), —B(Q₁)(Q₂), —C(═O)(Q₁),         —S(═O)₂(Q₁), or —P(═O)(Q₁)(Q₂),     -   b41 to b46 may each independently be an integer from 1 to 10,     -   at least one of substituents of the substituted C₅-C₃₀         carbocyclic group, the substituted C₁-C₃₀ heterocyclic group,         the substituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀         alkenyl group, the substituted C₂-C₆₀ alkynyl group, the         substituted C₁-C₆₀ alkoxy group, the substituted C₃-C₁₀         cycloalkyl group, the substituted C₁-C₁₀ heterocycloalkyl group,         the substituted C₃-C₁₀ cycloalkenyl group, the substituted         C₁-C₁₀heterocycloalkenyl group, the substituted C₆-C₆₀ aryl         group, the substituted C₆-C₆₀ aryloxy group, the substituted         C₆-C₆₀ arylthio group, the substituted C₁-C₆₀ heteroaryl group,         the substituted monovalent non-aromatic condensed polycyclic         group, and the substituted monovalent non-aromatic condensed         heteropolycyclic group may be:     -   deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amidino group, a hydrazino group, a hydrazono         group, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀         alkynyl group, or a C₁-C₆₀ alkoxy group;     -   a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl         group, or a C₁-C₆₀ alkoxy group, each substituted with         deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amidino group, a hydrazino group, a hydrazono         group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl         group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl         group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀         arylthio group, a C₁-C₆₀ heteroaryl group, a monovalent         non-aromatic condensed polycyclic group, a monovalent         non-aromatic condensed heteropolycyclic group,         —Si(Q₁₁)(Q₁₂)(Q₁₃), —N(Q₁₁)(Q₁₂), —B(Q₁₁)(Q₁₂), —C(═O)(Q₁₁),         —S(═O)₂(Q₁₁), —P(═O)(Q₁₁)(Q₁₂), or any combination thereof;     -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio         group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic         condensed polycyclic group, or a monovalent non-aromatic         condensed heteropolycyclic group;     -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio         group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic         condensed polycyclic group, or a monovalent non-aromatic         condensed heteropolycyclic group, each substituted with         deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amidino group, a hydrazino group, a hydrazono         group, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀         alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group,         a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a         C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀         aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl         group, a monovalent non-aromatic condensed polycyclic group, a         monovalent non-aromatic condensed heteropolycyclic group,         —Si(Q₂₁)(Q₂₂)(Q₂₃), —N(Q₂₁)(Q₂₂), —B(Q₂₁)(Q₂₂), —C(═O)(Q₂₁),         —S(═O)₂(Q₂₁), —P(═O)(Q₂₁)(Q₂₂), or any combination thereof; or     -   —Si(Q₃₁)(Q₃₂)(Q₃₃), —N(Q₃₁)(Q₃₂), —B(Q₃₁)(Q₃₂), —C(═O)(Q₃₁),         —S(═O)₂(Q₃₁), or —P(═O)(Q₃₁)(Q₃₂), and     -   Q₁ to Q₃, Q₁₁ to Q₁₃, Q₂₁ to Q₂₃, and Q₃₁ to Q₃₃ may each         independently be hydrogen, deuterium, —F, —Cl, —Br, —I, a         hydroxyl group, a cyano group, a nitro group, an amino group, an         amidino group, a hydrazino group, a hydrazono group, a C₁-C₆₀         alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a         C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀         heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀         heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryl         group substituted with a C₁-C₆₀ alkyl group, a C₆-C₆₀ aryl group         substituted with a C₆-C₆₀ aryl group, a C₁-C₆₀ heteroaryl group,         a monovalent non-aromatic condensed polycyclic group, a         monovalent non-aromatic condensed heteropolycyclic group, a         biphenyl group, or a terphenyl group, and     -   * may indicate a binding site to a neighboring atom.

In an embodiment, in Formula 1-11, CY₁₁ and CY₁₂ may each independently be a benzene group, a naphthalene group, an anthracene group, a phenanthrene group, a fluoranthene group, a triphenylene group, a pyrene group, a chrysene group, an indene group, a fluorene group, a spiro-bifluorene group, a benzofluorene group, a dibenzofluorene group, a carbazole group, a benzocarbazole group, a dibenzocarbazole group, a dibenzosilole group, a dibenzofuran group, or a dibenzothiophene group.

In an embodiment, in Formula 1-11, CY₁₁ and CY₁₂ may each independently be a benzene group, a naphthalene group, a phenanthrene group, a fluorene group, a carbazole group, a dibenzosilole group, a dibenzofuran group, or a dibenzothiophene group.

In an embodiment, in Formulae 1-11 to 1-14, L₄₁ to L₄₇ may each independently be a single bond or a substituted or unsubstituted π electron-rich cyclic group having 3 to 30 carbon atoms.

In an embodiment, in Formulae 1-11 to 1-14, L₄₁ to L₄₇ may each independently be:

-   -   a single bond, a benzene group, a heptalene group, an indene         group, a naphthalene group, an azulene group, a heptalene group,         an indacene group, an acenaphthylene group, a fluorene group, a         spiro-bifluorene group, a benzofluorene group, a dibenzofluorene         group, a phenalene group, a phenanthrene group, an anthracene         group, a fluoranthene group, a triphenylene group, a pyrene         group, a chrysene group, a naphthacene group, a picene group,         perylene group, a pentacene group, a hexacene group, a pentacene         group, a rubicene group, a corogene group, an ovalene group, a         pyrrole group, an iso-indole group, an indole group, a furan         group, a thiophene group, a benzofuran group, a benzothiophene         group, a benzosilole group, a benzocarbazole group, a         dibenzocarbazole group, a dibenzofuran group, a dibenzothiophene         group, a dibenzothiophene sulfone group, a carbazole group, a         dibenzosilole group, an indenocarbazole group, an         indolocarbazole group, a benzofurocarbazole group, a         benzothienocarbazole group, a benzosilolocarbazole group, a         triindolobenzene group, an acridine group, or a dihydroacridine         group; or     -   a benzene group, a heptalene group, an indene group, a         naphthalene group, an azulene group, a heptalene group, an         indacene group, an acenaphthylene group, a fluorene group, a         spiro-bifluorene group, a benzofluorene group, a dibenzofluorene         group, a phenalene group, a phenanthrene group, an anthracene         group, a fluoranthene group, a triphenylene group, a pyrene         group, a chrysene group, a naphthacene group, a picene group, a         perylene group, a pentacene group, a hexacene group, a pentacene         group, a rubicene group, a corogene group, an ovalene group, a         pyrrole group, an iso-indole group, an indole group, a furan         group, a thiophene group, a benzofuran group, a benzothiophene         group, a benzosilole group, a benzocarbazole group, a         dibenzocarbazole group, a dibenzofuran group, a dibenzothiophene         group, a dibenzothiophene sulfone group, a carbazole group, a         dibenzosilole group, an indenocarbazole group, an         indolocarbazole group, a benzofurocarbazole group, a         benzothienocarbazole group, a benzosilolocarbazole group, a         triindolobenzene group, an acridine group, or a dihydroacridine         group, each substituted with deuterium, a C₁-C₁₀ alkyl group, a         C₁-C₁₀ alkoxy group, a phenyl group, a naphthyl group, a         fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a         dibenzothiophenyl group, a triphenylenyl group, a biphenyl         group, a terphenyl group, or any combination thereof.

In Formulae 1-11 to 1-14, a41 to a47 respectively indicate numbers of L₄₁ to L₄₇, and may each independently an integer from 1 to 10.

In an embodiment, in Formulae 1-11 to 1-14, R₄₁ to R₄₆ may each independently be:

-   -   hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano         group, a nitro group, a C₁-C₂₀ alkyl group, or a C₁-C₂₀ alkoxy         group;     -   a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted         with deuterium, —F, —Cl, —Br, —I, a cyano group, a phenyl group,         a biphenyl group, or any combination thereof;     -   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a         cyclopentenyl group, a cyclohexenyl group, a phenyl group, a         biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl         group, a spiro-bifluorenyl group, a         spiro-fluorene-benzofluorenyl group, a benzofluorenyl group, a         dibenzofluorenyl group, a pyrenyl group, a phenalenyl group, a         phenanthrenyl group, an anthracenyl group, a fluoranthenyl         group, a triphenylenyl group, a pyrrolyl group, a thiophenyl         group, a furanyl group, a silolyl group, an imidazolyl group, a         pyrazolyl group, a thiazolyl group, an isothiazolyl group, an         oxazolyl group, an isoxazolyl group, a pyridinyl group, a         pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an         indolyl group, an isoindolyl group, an indazolyl group, a         purinyl group, a quinolinyl group, an isoquinolinyl group, a         benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl         group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl         group, a phenanthridinyl group, an acridinyl group, a         phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl         group, a benzofuranyl group, a benzothiophenyl group, a         benzosilolyl group, a benzoisothiazolyl group, a benzoxazolyl         group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl         group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl         group, a dibenzothiophenyl group, a dibenzosilolyl group, a         carbazolyl group, a benzocarbazolyl group, a dibenzocarbazolyl         group, a thiadiazolyl group, an imidazopyridinyl group, an         imidazopyrimidinyl group, an oxazolopyridinyl group, a         thiazolopyridinyl group, a benzonaphthyridinyl group, an         azafluorenyl group, an azaspiro-bifluorenyl group, an         azacarbazolyl group, an azadibenzofuranyl group, an         azadibenzothiophenyl group, an azadibenzosilolyl group,         —Si(Q₁)(Q₂)(Q₃), —N(Q₁)(Q₂), or —B(Q₁)(Q₂); or     -   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a         cyclopentenyl group, a cyclohexenyl group, a phenyl group, a         biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl         group, a spiro-bifluorenyl group, a         spiro-fluorene-benzofluorenyl group, a benzofluorenyl group, a         dibenzofluorenyl group, a pyrenyl group, a phenalenyl group, a         phenanthrenyl group, an anthracenyl group, a fluoranthenyl         group, a triphenylenyl group, a pyrrolyl group, a thiophenyl         group, a furanyl group, a silolyl group, an imidazolyl group, a         pyrazolyl group, a thiazolyl group, an isothiazolyl group, an         oxazolyl group, an isoxazolyl group, a pyridinyl group, a         pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an         indolyl group, an isoindolyl group, an indazolyl group, a         purinyl group, a quinolinyl group, an isoquinolinyl group, a         benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl         group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl         group, a phenanthridinyl group, an acridinyl group, a         phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl         group, a benzofuranyl group, a benzothiophenyl group, a         benzosilolyl group, a benzoisothiazolyl group, a benzoxazolyl         group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl         group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl         group, a dibenzothiophenyl group, a dibenzosilolyl group, a         carbazolyl group, a benzocarbazolyl group, a dibenzocarbazolyl         group, a thiadiazolyl group, an imidazopyridinyl group, an         imidazopyrimidinyl group, an oxazolopyridinyl group, a         thiazolopyridinyl group, a benzonaphthyridinyl group, an         azafluorenyl group, an azaspiro-bifluorenyl group, an         azacarbazolyl group, an azadibenzofuranyl group, an         azadibenzothiophenyl group, or an azadibenzosilolyl group, each         substituted with deuterium, —F, —Cl, —Br, —I, a hydroxyl group,         a cyano group, a nitro group, an amidino group, a hydrazino         group, a hydrazono group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy         group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl         group, a cyclopentenyl group, a cyclohexenyl group, a phenyl         group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl         group, a spiro-fluorene-benzofluorenyl group, a benzofluorenyl         group, a dibenzofluorenyl group, a pyrenyl group, a phenalenyl         group, a phenanthrenyl group, an anthracenyl group, a         fluoranthenyl group, a triphenylenyl group, a pyrrolyl group, a         thiophenyl group, a furanyl group, a silolyl group, an         imidazolyl group, a pyrazolyl group, a thiazolyl group, an         isothiazolyl group, an oxazolyl group, an isoxazolyl group, a         pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a         pyridazinyl group, an indolyl group, an isoindolyl group, an         indazolyl group, a purinyl group, a quinolinyl group, an         isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl         group, a naphthyridinyl group, a quinoxalinyl group, a         quinazolinyl group, a cinnolinyl group, a phenanthridinyl group,         an acridinyl group, a phenanthrolinyl group, a phenazinyl group,         a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl         group, a benzosilolyl group, a benzoisothiazolyl group, a         benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group,         a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a         dibenzofuranyl group, a dibenzothiophenyl group, a         dibenzosilolyl group, a carbazolyl group, a benzocarbazolyl         group, a dibenzocarbazolyl group, a thiadiazolyl group, an         imidazopyridinyl group, an imidazopyrimidinyl group, an         oxazolopyridinyl group, a thiazolopyridinyl group, a         benzonaphthyridinyl group, an azafluorenyl group, an         azaspiro-bifluorenyl group, an azacarbazolyl group, an         azadibenzofuranyl group, an azadibenzothiophenyl group, an         azadibenzosilolyl group, a biphenyl group, a terphenyl group, or         any combination thereof, and     -   Q₁ to Q₃ may each independently be hydrogen, deuterium, a C₁-C₁₀         alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, a naphthyl         group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl         group, a dibenzothiophenyl group, a triphenylenyl group, a         biphenyl group, a terphenyl group, or a tetraphenyl group.

In an embodiment, in Formulae 1-11 to 1-14, R₄₁ to R₄₆ may each independently be hydrogen, a substituted or unsubstituted monovalent π electron-rich cyclic group, —Si(Q₁)(Q₂)(Q₃), or —N(Q₁)(Q₂), and

-   -   Q₁ to Q₃ may each independently be hydrogen, deuterium, a C₁-C₁₀         alkyl group, a C₁-C₁₀ alkoxy group, a π electron-rich cyclic         group, a biphenyl group, or a terphenyl group.

In an embodiment, in Formulae 1-11 to 1-14, R₄₁ to R₄₆ may each independently be:

-   -   a phenyl group, a biphenyl group, a terphenyl group, a         tetraphenyl group, a naphthyl group, a fluorenyl group, a         spiro-bifluorenyl group, a benzofluorenyl group, a         dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl         group, a triphenylenyl group, a pyrenyl group, a chrysenyl         group, a pyrrolyl group, an isoindolyl group, an indolyl group,         a furanyl group, a thiophenyl group, a benzofuranyl group, a         benzothiophenyl group, a benzosilolyl group, a dibenzofuranyl         group, a dibenzothiophenyl group, a carbazolyl group, a         benzocarbazolyl group, a dibenzocarbazolyl group, a         dibenzosilolyl group, an indenocarbazolyl group, an         indolocarbazolyl group, a benzofurocarbazolyl group, a         benzothienocarbazolyl group, a benzosilolocarbazolyl group, an         acridinyl group, or a dihydroacridinyl group;     -   a phenyl group, a biphenyl group, a terphenyl group, a         tetraphenyl group, a naphthyl group, a fluorenyl group, a         spiro-bifluorenyl group, a benzofluorenyl group, a         dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl         group, a triphenylenyl group, a pyrenyl group, a chrysenyl         group, a pyrrolyl group, an isoindolyl group, an indolyl group,         a furanyl group, a thiophenyl group, a benzofuranyl group, a         benzothiophenyl group, a benzosilolyl group, a dibenzofuranyl         group, a dibenzothiophenyl group, a carbazolyl group, a         benzocarbazolyl group, a dibenzocarbazolyl group, a         dibenzosilolyl group, an indenocarbazolyl group, an         indolocarbazolyl group, a benzofurocarbazolyl group, a         benzothienocarbazolyl group, a benzosilolocarbazolyl group, an         acridinyl group, or a dihydroacridinyl group, each substituted         with deuterium, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a         phenyl group, a naphthyl group, a fluorenyl group, a carbazolyl         group, a dibenzofuranyl group, a dibenzothiophenyl group, a         triphenylenyl group, a biphenyl group, a terphenyl group, or any         combination thereof; or     -   —Si(Q₁)(Q₂)(Q₃) or —N(Q₁)(Q₂), and     -   Q₁ to Q₃ may each independently be hydrogen, deuterium, a C₁-C₁₀         alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, a naphthyl         group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl         group, a dibenzothiophenyl group, a triphenylenyl group, a         biphenyl group, or a terphenyl group.

In Formulae 1-11 to 1-14, b41 to b46 respectively indicate numbers of R₄₁ to R₄₆, and may each independently be an integer from 1 to 10.

In an embodiment, the first compound may be one of the following compounds, but embodiments are not limited thereto:

[Second Compound]

The second compound may include at least one electron transporting moiety.

In an embodiment, the second compound may include —F, a cyano group, a C₁-C₆₀ alkyl group that is substituted with —F or a cyano group, a C₆-C₆₀ aryl group that is substituted with —F or a cyano group, a π electron-deficient nitrogen-containing cyclic group, or any combination thereof.

In an embodiment, the second compound may be a compound represented by Formula 2-1:

In Formula 2-1,

-   -   X₂₁ may be N or C[(L₂₄)_(a24)-(R₂₄)_(b24)], X₂₂ may be N or         C[(L₂₅)_(a25)-(R₂₅)_(b25)], and X₂₃ may be N or         C[(L₂₆)_(a26)-(R₂₆)_(b26)],     -   L₂₁ to L₂₆ may each independently be a single bond, a         substituted or unsubstituted C₅-C₃₀ carbocyclic group, or a         substituted or unsubstituted C₁-C₃₀ heterocyclic group,     -   a21 to a26 may each independently be an integer from 0 to 10,     -   R₂₁ to R₂₆ may each independently be hydrogen, deuterium, —F,         —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amidino group, a hydrazine group, a hydrazone group, a         carboxylic acid group or a salt thereof, a sulfonic acid group         or a salt thereof, a phosphoric acid group or a salt thereof, a         substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted         or unsubstituted C₂-C₆₀ alkenyl group, a substituted or         unsubstituted C₂-C₆₀ alkynyl group, a substituted or         unsubstituted C₁-C₆₀ alkoxy group, a substituted or         unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or         unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or         unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted         C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀         arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl         group, a substituted or unsubstituted monovalent non-aromatic         condensed polycyclic group, a substituted or unsubstituted         monovalent non-aromatic condensed heteropolycyclic group,         —Si(Q₁)(Q₂)(Q₃), —N(Q₁)(Q₂), —B(Q₁)(Q₂), —C(═O)(Q₁),         —S(═O)₂(Q₁), or —P(═O)(Q₁)(Q₂),     -   b21 to b26 may each independently be an integer from 1 to 10,         and     -   at least one of substituents of the substituted C₅-C₃₀         carbocyclic group, the substituted C₁-C₃₀ heterocyclic group,         the substituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀         alkenyl group, the substituted C₂-C₆₀ alkynyl group, the         substituted C₁-C₆₀ alkoxy group, the substituted C₃-C₁₀         cycloalkyl group, the substituted C₁-C₁₀ heterocycloalkyl group,         the substituted C₃-C₁₀ cycloalkenyl group, the substituted         C₁-C₁₀heterocycloalkenyl group, the substituted C₆-C₆₀ aryl         group, the substituted C₆-C₆₀ aryloxy group, the substituted         C₆-C₆₀ arylthio group, the substituted C₁-C₆₀ heteroaryl group,         the substituted monovalent non-aromatic condensed polycyclic         group, and the substituted monovalent non-aromatic condensed         heteropolycyclic group may be the same as described herein.

In an embodiment, in Formula 2-1, L₂₁ to L₂₆ may each independently be: a single bond, a benzene group, a naphthalene group, a fluorene group, a spiro-bifluorene group, a benzofluorene group, a dibenzofluorene group, a phenalene group, a phenanthrene group, an anthracene group, a fluoranthene group, a triphenylene group, a pyrene group, a chrysene group, a naphthacene group, a picene group, a perylene group, a pentaphene group, a dibenzofuran group, a dibenzothiophene group, a carbazole group, an imidazole group, a pyrazole group, a thiazole group, an isothiazole group, an oxazole group, an isoxazole group, a pyridine group, a pyrazine group, a pyridazine group, a pyrimidine group, an indazole group, a purine group, a quinoline group, an isoquinoline group, a benzoquinoline group, a benzoisoquinoline group, a phthalazine group, a naphthyridine group, a quinoxaline group, a benzoquinoxaline group, a quinazoline group, a cinnoline group, a phenanthridine group, a phenanthroline group, a phenazine group, a benzimidazole group, an isobenzothiazole group, a benzoxazole group, a benzoisoxazole group, a triazole group, a tetrazole group, an oxadiazole group, a triazine group, a thiadiazole group, an imidazopyridine group, an imidazopyrimidine group, an azaindene group, an azaindole group, an azabenzofuran group, an azabenzothiophene group, an azabenzosilole group, an azafluorene group, an azacarbazole group, an azadibenzofuran group, an azadibenzothiophene group, or an azadibenzosilole group; or

-   -   a benzene group, a naphthalene group, a fluorene group, a         spiro-bifluorene group, a benzofluorene group, a dibenzofluorene         group, a phenalene group, a phenanthrene group, an anthracene         group, a fluoranthene group, a triphenylene group, a pyrene         group, a chrysene group, a naphthacene group, a picene group, a         perylene group, a pentaphene group, a dibenzofuran group, a         dibenzothiophene group, a carbazole group, an imidazole group, a         pyrazole group, a thiazole group, an isothiazole group, an         oxazole group, an isoxazole group, a pyridine group, a pyrazine         group, a pyridazine group, a pyrimidine group, an indazole         group, a purine group, a quinoline group, an isoquinoline group,         a benzoquinoline group, a benzoisoquinoline group, a phthalazine         group, a naphthyridine group, a quinoxaline group, a         benzoquinoxaline group, a quinazoline group, a cinnoline group,         a phenanthridine group, a phenanthroline group, a phenazine         group, a benzimidazole group, an isobenzothiazole group, a         benzoxazole group, a benzoisoxazole group, a triazole group, a         tetrazole group, an oxadiazole group, a triazine group, a         thiadiazole group, an imidazopyridine group, an         imidazopyrimidine group, an azaindene group, an azaindole group,         an azabenzofuran group, an azabenzothiophene group, an         azabenzosilole group, an azafluorene group, an azacarbazole         group, an azadibenzofuran group, an azadibenzothiophene group,         or an azadibenzosilole group, each substituted with deuterium,         —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro         group, an amidino group, a hydrazino group, a hydrazono group, a         C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a         naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl         group, a phenanthrenyl group, an anthracenyl group, a         fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a         chrysenyl group, a naphthacenyl group, a picenyl group, a         perylenyl group, a pentaphenyl group, a dibenzofuranyl group, a         dibenzothiophenyl group, a carbazolyl group, an imidazolyl         group, a pyrazolyl group, a thiazolyl group, an isothiazolyl         group, an oxazolyl group, an isoxazolyl group, a pyridinyl         group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl         group, an indazolyl group, a purinyl group, a quinolinyl group,         an isoquinolinyl group, a benzoquinolinyl group, a         benzoisoquinolinyl group, a phthalazinyl group, a naphthyridinyl         group, a quinoxalinyl group, a benzoquinoxalinyl group, a         quinazolinyl group, a cinnolinyl group, a phenanthridinyl group,         a phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl         group, a benzoisothiazolyl group, a benzoxazolyl group, an         isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an         oxadiazolyl group, a triazinyl group, a thiadiazolyl group, an         imidazopyridinyl group, an imidazopyrimidinyl group, an         azaindenyl group, an azaindolyl group, an azabenzofuranyl group,         an azabenzothiophenyl group, an azabenzosilolyl group, an         azafluorenyl group, an azacarbazolyl group, an azadibenzofuranyl         group, an azadibenzothiophenyl group, an azadibenzosilolyl         group, —Si(Q₃₁)(Q₃₂)(Q₃₃), —N(Q₃₁)(Q₃₂), —B(Q₃₁)(Q₃₂),         —C(═O)(Q₃₁), —S(═O)₂(Q₃₁), —P(═O)(Q₃₁)(Q₃₂), or any combination         thereof, and     -   Q₃₁ to Q₃₃ may each independently be a C₁-C₁₀ alkyl group, a         C₁-C₁₀ alkoxy group, a phenyl group, a phenyl group substituted         with a C₁-C₁₀ alkyl group, a biphenyl group, a terphenyl group,         or a naphthyl group.

In an embodiment, in Formula 2-1, R₂₁ to R₂₆ may each independently be:

-   -   hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano         group, a nitro group, a C₁-C₂₀ alkyl group, or a C₁-C₂₀ alkoxy         group;     -   a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted         with deuterium, —F, —Cl, —Br, —I, a cyano group, a phenyl group,         a biphenyl group, or any combination thereof;     -   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a         cyclopentenyl group, a cyclohexenyl group, a phenyl group, a         biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl         group, a spiro-bifluorenyl group, a         spiro-fluorene-benzofluorenyl group, a benzofluorenyl group, a         dibenzofluorenyl group, a pyrenyl group, a phenalenyl group, a         phenanthrenyl group, an anthracenyl group, a fluoranthenyl         group, a triphenylenyl group, a pyrrolyl group, a thiophenyl         group, a furanyl group, a silolyl group, an imidazolyl group, a         pyrazolyl group, a thiazolyl group, an isothiazolyl group, an         oxazolyl group, an isoxazolyl group, a pyridinyl group, a         pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an         indolyl group, an isoindolyl group, an indazolyl group, a         purinyl group, a quinolinyl group, an isoquinolinyl group, a         benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl         group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl         group, a phenanthridinyl group, an acridinyl group, a         phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl         group, a benzofuranyl group, a benzothiophenyl group, a         benzosilolyl group, a benzoisothiazolyl group, a benzoxazolyl         group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl         group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl         group, a dibenzothiophenyl group, a dibenzosilolyl group, a         carbazolyl group, a benzocarbazolyl group, a dibenzocarbazolyl         group, a thiadiazolyl group, an imidazopyridinyl group, an         imidazopyrimidinyl group, an oxazolopyridinyl group, a         thiazolopyridinyl group, a benzonaphthyridinyl group, an         azafluorenyl group, an azaspiro-bifluorenyl group, an         azacarbazolyl group, an azadibenzofuranyl group, an         azadibenzothiophenyl group, an azadibenzosilolyl group,         —Si(Q₁)(Q₂)(Q₃), —N(Q₁)(Q₂), or —B(Q₁)(Q₂); or     -   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a         cyclopentenyl group, a cyclohexenyl group, a phenyl group, a         biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl         group, a spiro-bifluorenyl group, a         spiro-fluorene-benzofluorenyl group, a benzofluorenyl group, a         dibenzofluorenyl group, a pyrenyl group, a phenalenyl group, a         phenanthrenyl group, an anthracenyl group, a fluoranthenyl         group, a triphenylenyl group, a pyrrolyl group, a thiophenyl         group, a furanyl group, a silolyl group, an imidazolyl group, a         pyrazolyl group, a thiazolyl group, an isothiazolyl group, an         oxazolyl group, an isoxazolyl group, a pyridinyl group, a         pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an         indolyl group, an isoindolyl group, an indazolyl group, a         purinyl group, a quinolinyl group, an isoquinolinyl group, a         benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl         group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl         group, a phenanthridinyl group, an acridinyl group, a         phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl         group, a benzofuranyl group, a benzothiophenyl group, a         benzosilolyl group, a benzoisothiazolyl group, a benzoxazolyl         group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl         group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl         group, a dibenzothiophenyl group, a dibenzosilolyl group, a         carbazolyl group, a benzocarbazolyl group, a dibenzocarbazolyl         group, a thiadiazolyl group, an imidazopyridinyl group, an         imidazopyrimidinyl group, an oxazolopyridinyl group, a         thiazolopyridinyl group, a benzonaphthyridinyl group, an         azafluorenyl group, an azaspiro-bifluorenyl group, an         azacarbazolyl group, an azadibenzofuranyl group, an         azadibenzothiophenyl group, or an azadibenzosilolyl group, each         substituted with deuterium, —F, —Cl, —Br, —I, a hydroxyl group,         a cyano group, a nitro group, an amidino group, a hydrazino         group, a hydrazono group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy         group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl         group, a cyclopentenyl group, a cyclohexenyl group, a phenyl         group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl         group, a spiro-fluorene-benzofluorenyl group, a benzofluorenyl         group, a dibenzofluorenyl group, a pyrenyl group, a phenalenyl         group, a phenanthrenyl group, an anthracenyl group, a         fluoranthenyl group, a triphenylenyl group, a pyrrolyl group, a         thiophenyl group, a furanyl group, a silolyl group, an         imidazolyl group, a pyrazolyl group, a thiazolyl group, an         isothiazolyl group, an oxazolyl group, an isoxazolyl group, a         pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a         pyridazinyl group, an indolyl group, an isoindolyl group, an         indazolyl group, a purinyl group, a quinolinyl group, an         isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl         group, a naphthyridinyl group, a quinoxalinyl group, a         quinazolinyl group, a cinnolinyl group, a phenanthridinyl group,         an acridinyl group, a phenanthrolinyl group, a phenazinyl group,         a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl         group, a benzosilolyl group, a benzoisothiazolyl group, a         benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group,         a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a         dibenzofuranyl group, a dibenzothiophenyl group, a         dibenzosilolyl group, a carbazolyl group, a benzocarbazolyl         group, a dibenzocarbazolyl group, a thiadiazolyl group, an         imidazopyridinyl group, an imidazopyrimidinyl group, an         oxazolopyridinyl group, a thiazolopyridinyl group, a         benzonaphthyridinyl group, an azafluorenyl group, an         azaspiro-bifluorenyl group, an azacarbazolyl group, an         azadibenzofuranyl group, an azadibenzothiophenyl group, an         azadibenzosilolyl group, a biphenyl group, a terphenyl group, or         any combination thereof, and     -   Q₁ to Q₃ may each independently be hydrogen, deuterium, a C₁-C₁₀         alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, a naphthyl         group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl         group, a dibenzothiophenyl group, a triphenylenyl group, a         biphenyl group, a terphenyl group, or a tetraphenyl group.

In an embodiment, the second compound may be one of the following compounds, but embodiments are not limited thereto:

The organic light-emitting device may include a mixed host of the first compound and the second compound. Therefore, charge balance of the emission layer may be improved as compared to organic light-emitting devices including a single host.

In an embodiment, when the first compound and the second compound are each a host that transports charges (holes or electrons) having different characteristics, driving characteristics of the organic light-emitting device may be improved by maintaining balance between holes and electrons in the emission layer. For example, the efficiency of the organic light-emitting device may be improved by optimizing the exciton profile in the emission layer. The first compound and the second compound may form an exciplex.

In an embodiment, a host in the emission layer may include a compound represented by Formula 301.

[Ar₃₀₁]_(xb11)-[(L₃₀₁)_(xb1)-R₃₀₁]_(xb21)  [Formula 301]

In Formula 301,

-   -   Ar₃₀₁ may be a substituted or unsubstituted C₅-C₆₀ carbocyclic         group or a substituted or unsubstituted C₁-C₆₀ heterocyclic         group,     -   xb11 may be 1, 2, or 3,     -   L₃₀₁ may be a substituted or unsubstituted C₃-C₁₀ cycloalkylene         group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkylene         group, a substituted or unsubstituted C₃-C₁₀ cycloalkenylene         group, a substituted or unsubstituted C₁-C₁₀         heterocycloalkenylene group, a substituted or unsubstituted         C₆-C₆₀ arylene group, a substituted or unsubstituted C₁-C₆₀         heteroarylene group, a substituted or unsubstituted divalent         non-aromatic condensed polycyclic group, or a substituted or         unsubstituted divalent non-aromatic condensed heteropolycyclic         group,     -   xb1 may be an integer from 0 to 5,     -   R₃₀₁ may be hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl         group, a cyano group, a nitro group, an amidino group, a         hydrazino group, a hydrazono group, a substituted or         unsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted         C₂-C₆₀ alkenyl group, a substituted or unsubstituted C₂-C₆₀         alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxy         group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a         substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a         substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a         substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a         substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or         unsubstituted C₆-C₆₀ aryloxy group, a substituted or         unsubstituted C₆-C₆₀ arylthio group, a substituted or         unsubstituted C₁-C₆₀ heteroaryl group, a substituted or         unsubstituted monovalent non-aromatic condensed polycyclic         group, a substituted or unsubstituted monovalent non-aromatic         condensed heteropolycyclic group, —Si(Q₃₀₁)(Q₃₀₂)(Q₃₀₃),         —N(Q₃₀₁)(Q₃₀₂), —B(Q₃₀₁)(Q₃₀₂), —C(═O)(Q₃₀₁), —S(═O)₂(Q₃₀₁), or         —P(═O)(Q₃₀₁)(Q₃₀₂),     -   xb21 may be an integer from 1 to 5, and     -   Q₃₀₁ to Q₃₀₃ may each independently be a C₁-C₁₀ alkyl group, a         C₁-C₁₀ alkoxy group, a phenyl group, a biphenyl group, a         terphenyl group, or a naphthyl group, but embodiments are not         limited thereto.

In an embodiment, in Formula 301, Ar₃₀₁ may be:

-   -   a naphthalene group, a fluorene group, a spiro-bifluorene group,         a benzofluorene group, a dibenzofluorene group, a phenalene         group, a phenanthrene group, an anthracene group, a fluoranthene         group, a triphenylene group, a pyrene group, a chrysene group, a         naphthacene group, a picene group, a perylene group, a         pentaphene group, an indenoanthracene group, a dibenzofuran         group, or a dibenzothiophene group; or     -   a naphthalene group, a fluorene group, a spiro-bifluorene group,         a benzofluorene group, a dibenzofluorene group, a phenalene         group, a phenanthrene group, an anthracene group, a fluoranthene         group, a triphenylene group, a pyrene group, a chrysene group, a         naphthacene group, a picene group, a perylene group, a         pentaphene group, an indenoanthracene group, a dibenzofuran         group, or a dibenzothiophene group, each substituted with         deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amidino group, a hydrazino group, a hydrazono         group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl         group, a biphenyl group, a terphenyl group, a naphthyl group,         —Si(Q₃₁)(Q₃₂)(Q₃₃), —N(Q₃₁)(Q₃₂), —B(Q₃₁)(Q₃₂), —C(═O)(Q₃₁),         —S(═O)₂(Q₃₁), —P(═O)(Q₃₁)(Q₃₂), or any combination thereof, and     -   Q₃₁ to Q₃₃ may each independently be a C₁-C₁₀ alkyl group, a         C₁-C₁₀ alkoxy group, a phenyl group, a biphenyl group, a         terphenyl group, or a naphthyl group, but embodiments are not         limited thereto.

In an embodiment, in Formula 301, when xb11 is two or more, two or more Ar₃₀₁(s) may be linked to each other via a single bond.

In an embodiment, the compound represented by Formula 301 may be represented by Formula 301-1 or Formula 301-2:

In Formulae 301-1 and 301-2,

-   -   A₃₀₁ to A₃₀₄ may each independently be a benzene, a naphthalene,         a phenanthrene, a fluoranthene, a triphenylene, a pyrene, a         chrysene, a pyridine, a pyrimidine, an indene, a fluorene, a         spiro-bifluorene, a benzofluorene, a dibenzofluorene, an indole,         a carbazole, a benzocarbazole, a dibenzocarbazole, a furan, a         benzofuran, a dibenzofuran, a naphthofuran, a benzonaphthofuran,         a dinaphthofuran, a thiophene, a benzothiophene, a         dibenzothiophene, a naphthothiophene, a benzonaphthothiophene,         or a dinaphthothiophene,     -   X₃₀₁ may be O, S, or N—[(L₃₀₄)_(xb4)-R₃₀₄],     -   R₃₁₁ to R₃₁₄ may each independently be hydrogen, deuterium, —F,         —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amidino group, a hydrazino group, a hydrazono group, a C₁-C₂₀         alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a biphenyl         group, a terphenyl group, a naphthyl group —Si(Q₃₁)(Q₃₂)(Q₃₃),         —N(Q₃₁)(Q₃₂), —B(Q₃₁)(Q₃₂), —C(═O)(Q₃₁), —S(═O)₂(Q₃₁), or         —P(═O)(Q₃₁)(Q₃₂),     -   xb22 and xb23 may each independently be 0, 1, or 2,     -   L₃₀₁, xb1, R₃₀₁ and Q₃₁ to Q₃₃ may each be the same as described         in the specification,     -   L₃₀₂ to L₃₀₄ may each independently be the same as described in         connection with L₃₀₁,     -   xb2 to xb4 may each independently be the same as described in         connection with xb1, and     -   R₃₀₂ to R₃₀₄ may each independently be the same as described in         connection with R₃₀₁.

In an embodiment, in Formulae 301, 301-1, and 301-2, L₃₀₁ to L₃₀₄ may each independently be:

-   -   a phenylene group, a naphthylene group, a fluorenylene group, a         spiro-bifluorenylene group, a benzofluorenylene group, a         dibenzofluorenylene group, a phenanthrenylene group, an         anthracenylene group, a fluoranthenylene group, a         triphenylenylene group, a pyrenylene group, a chrysenylene         group, a perylenylene group, a pentaphenylene group, a         hexacenylene group, a pentacenylene group, a thiophenylene         group, a furanylene group, a carbazolylene group, an indolylene         group, an isoindolylene group, a benzofuranylene group, a         benzothiophenylene group, a dibenzofuranylene group, a         dibenzothiophenylene group, a benzocarbazolylene group, a         dibenzocarbazolylene group, a dibenzosilolylene group, a         pyridinylene group, an imidazolylene group, a pyrazolylene         group, a thiazolylene group, an isothiazolylene group, an         oxazolylene group, an isoxazolylene group, a thiadiazolylene         group, an oxadiazolylene group, a pyrazinylene group, a         pyrimidinylene group, a pyridazinylene group, a triazinylene         group, a quinolinylene group, an isoquinolinylene group, a         benzoquinolinylene group, a phthalazinylene group, a         naphthyridinylene group, a quinoxalinylene group, a         quinazolinylene group, a cinnolinylene group, a         phenanthridinylene group, an acridinylene group, a         phenanthrolinylene group, a phenazinylene group, a         benzimidazolylene group, an isobenzothiazolylene group, a         benzoxazolylene group, an isobenzoxazolylene group, a         triazolylene group, a tetrazolylene group, an         imidazopyridinylene group, an imidazopyrimidinylene group, or an         azacarbazolylene group; or     -   a phenylene group, a naphthylene group, a fluorenylene group, a         spiro-bifluorenylene group, a benzofluorenylene group, a         dibenzofluorenylene group, a phenanthrenylene group, an         anthracenylene group, a fluoranthenylene group, a         triphenylenylene group, a pyrenylene group, a chrysenylene         group, a perylenylene group, a pentaphenylene group, a         hexacenylene group, a pentacenylene group, a thiophenylene         group, a furanylene group, a carbazolylene group, an indolylene         group, an isoindolylene group, a benzofuranylene group, a         benzothiophenylene group, a dibenzofuranylene group, a         dibenzothiophenylene group, a benzocarbazolylene group, a         dibenzocarbazolylene group, a dibenzosilolylene group, a         pyridinylene group, an imidazolylene group, a pyrazolylene         group, a thiazolylene group, an isothiazolylene group, an         oxazolylene group, an isoxazolylene group, a thiadiazolylene         group, an oxadiazolylene group, a pyrazinylene group, a         pyrimidinylene group, a pyridazinylene group, a triazinylene         group, a quinolinylene group, an isoquinolinylene group, a         benzoquinolinylene group, a phthalazinylene group, a         naphthyridinylene group, a quinoxalinylene group, a         quinazolinylene group, a cinnolinylene group, a         phenanthridinylene group, an acridinylene group, a         phenanthrolinylene group, a phenazinylene group, a         benzimidazolylene group, an isobenzothiazolylene group, a         benzoxazolylene group, an isobenzoxazolylene group, a         triazolylene group, a tetrazolylene group, an         imidazopyridinylene group, an imidazopyrimidinylene group, or an         azacarbazolylene group, each substituted with deuterium, —F,         —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amidino group, a hydrazino group, a hydrazono group, a C₁-C₂₀         alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a biphenyl         group, a terphenyl group, a naphthyl group, a fluorenyl group, a         spiro-bifluorenyl group, a benzofluorenyl group, a         dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl         group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl         group, a chrysenyl group, a perylenyl group, a pentaphenyl         group, a hexacenyl group, a pentacenyl group, a thiophenyl         group, a furanyl group, a carbazolyl group, an indolyl group, an         isoindolyl group, a benzofuranyl group, a benzothiophenyl group,         a dibenzofuranyl group, a dibenzothiophenyl group, a         benzocarbazolyl group, a dibenzocarbazolyl group, a         dibenzosilolyl group, a pyridinyl group, an imidazolyl group, a         pyrazolyl group, a thiazolyl group, an isothiazolyl group, an         oxazolyl group, an isoxazolyl group, a thiadiazolyl group, an         oxadiazolyl group, a pyrazinyl group, a pyrimidinyl group, a         pyridazinyl group, a triazinyl group, a quinolinyl group, an         isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl         group, a naphthyridinyl group, a quinoxalinyl group, a         quinazolinyl group, a cinnolinyl group, a phenanthridinyl group,         an acridinyl group, a phenanthrolinyl group, a phenazinyl group,         a benzimidazolyl group, an isobenzothiazolyl group, a         benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group,         a tetrazolyl group, an imidazopyridinyl group, an         imidazopyrimidinyl group, an azacarbazolyl group,         —Si(Q₃₁)(Q₃₂)(Q₃₃), —N(Q₃₁)(Q₃₂), —B(Q₃₁)(Q₃₂), —C(═O)(Q₃₁),         —S(═O)₂(Q₃₁), —P(═O)(Q₃₁)(Q₃₂), or any combination thereof, and     -   Q₃₁ to Q₃₃ may each be the same as described in the         specification.

In an embodiment, in Formulae 301, 301-1, and 301-2, R₃₀₁ to R₃₀₄ may each independently be:

-   -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-bifluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a fluoranthenyl group, a         triphenylenyl group, a pyrenyl group, a chrysenyl group, a         perylenyl group, a pentaphenyl group, a hexacenyl group, a         pentacenyl group, a thiophenyl group, a furanyl group, a         carbazolyl group, an indolyl group, an isoindolyl group, a         benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl         group, a dibenzothiophenyl group, a benzocarbazolyl group, a         dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl         group, an imidazolyl group, a pyrazolyl group, a thiazolyl         group, an isothiazolyl group, an oxazolyl group, an isoxazolyl         group, a thiadiazolyl group, an oxadiazolyl group, a pyrazinyl         group, a pyrimidinyl group, a pyridazinyl group, a triazinyl         group, a quinolinyl group, an isoquinolinyl group, a         benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl         group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl         group, a phenanthridinyl group, an acridinyl group, a         phenanthrolinyl group, a phenazinyl group, a benzimidazolyl         group, an isobenzothiazolyl group, a benzoxazolyl group, an         isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an         imidazopyridinyl group, an imidazopyrimidinyl group, or an         azacarbazolyl group; or     -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-bifluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a fluoranthenyl group, a         triphenylenyl group, a pyrenyl group, a chrysenyl group, a         perylenyl group, a pentaphenyl group, a hexacenyl group, a         pentacenyl group, a thiophenyl group, a furanyl group, a         carbazolyl group, an indolyl group, an isoindolyl group, a         benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl         group, a dibenzothiophenyl group, a benzocarbazolyl group, a         dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl         group, an imidazolyl group, a pyrazolyl group, a thiazolyl         group, an isothiazolyl group, an oxazolyl group, an isoxazolyl         group, a thiadiazolyl group, an oxadiazolyl group, a pyrazinyl         group, a pyrimidinyl group, a pyridazinyl group, a triazinyl         group, a quinolinyl group, an isoquinolinyl group, a         benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl         group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl         group, a phenanthridinyl group, an acridinyl group, a         phenanthrolinyl group, a phenazinyl group, a benzimidazolyl         group, an isobenzothiazolyl group, a benzoxazolyl group, an         isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an         imidazopyridinyl group, an imidazopyrimidinyl group, or an         azacarbazolyl group, each substituted with deuterium, —F, —Cl,         —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amidino group, a hydrazino group, a hydrazono group, a C₁-C₂₀         alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a biphenyl         group, a terphenyl group, a naphthyl group, a fluorenyl group, a         spiro-bifluorenyl group, a benzofluorenyl group, a         dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl         group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl         group, a chrysenyl group, a perylenyl group, a pentaphenyl         group, a hexacenyl group, a pentacenyl group, a thiophenyl         group, a furanyl group, a carbazolyl group, an indolyl group, an         isoindolyl group, a benzofuranyl group, a benzothiophenyl group,         a dibenzofuranyl group, a dibenzothiophenyl group, a         benzocarbazolyl group, a dibenzocarbazolyl group, a         dibenzosilolyl group, a pyridinyl group, an imidazolyl group, a         pyrazolyl group, a thiazolyl group, an isothiazolyl group, an         oxazolyl group, an isoxazolyl group, a thiadiazolyl group, an         oxadiazolyl group, a pyrazinyl group, a pyrimidinyl group, a         pyridazinyl group, a triazinyl group, a quinolinyl group, an         isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl         group, a naphthyridinyl group, a quinoxalinyl group, a         quinazolinyl group, a cinnolinyl group, a phenanthridinyl group,         an acridinyl group, a phenanthrolinyl group, a phenazinyl group,         a benzimidazolyl group, an isobenzothiazolyl group, a         benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group,         a tetrazolyl group, an imidazopyridinyl group, an         imidazopyrimidinyl group, an azacarbazolyl group,         —Si(Q₃₁)(Q₃₂)(Q₃₃), —N(Q₃₁)(Q₃₂), —B(Q₃₁)(Q₃₂), —C(═O)(Q₃₁),         —S(═O)₂(Q₃₁), —P(═O)(Q₃₁)(Q₃₂), or any combination thereof, and     -   Q₃₁ to Q₃₃ may each be the same as described in the         specification.

In an embodiment, the host may include an alkaline earth-metal complex. In an embodiment, the host may include a Be complex (for example, Compound H55), an Mg complex, a Zn complex, or any combination thereof.

In an embodiment, the host may include 9,10-Di(2-naphthyl)anthracene (ADN), 2-methyl-9,10-bis(naphthalen-2-yl)anthracene (MADN), 9,10-di-(2-naphthyl)-2-t-butyl-anthracene (TBADN), 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP), 1,3-di-9-carbazolylbenzene (mCP), 1,3,5-tri(carbazol-9-yl)benzene (TCP), one of Compounds H1 to H55, or any combination thereof, but embodiments are not limited thereto:

[Third Compound]

In an embodiment, the third compound may be represented by Formula 3:

In Formula 3,

-   -   CY₁ to CY₄ may each independently be a C₅-C₃₀ carbocyclic group         or a C₁-C₃₀ heterocyclic group,     -   L₁ to L₃ may each independently be a single bond, a double bond,         a substituted or unsubstituted C₆-C₃₀ arylene group, a         substituted or unsubstituted C₁-C₃₀ heteroarylene group, *—O—*′,         *—S—*′, *—C(═O)—*′, *—S(═O)—*′, *—C(Q₁)(Q₂)-*′,         *—C(Q₁)=C(Q₂)-*′, *—C(Q₁)=*′, *—Si(Q₁)(Q₂)-*′, *—B(Q₁)-*′,         *—N(Q₁)-*′, or *—P(Q₁)-*′,     -   T₁ to T₄ may each independently be a chemical bond, *—O—*′,         *—S—*′, *—B(Q₃)-*′, *—N(Q₃)-*′, *—P(Q₃)-*′, *—C(Q₃)(Q₄)-*,         *—Si(Q₃)(Q₄)-*′, *—Ge(Q₃)(Q₄)-*′, *—C(═O)—*′, or *—C(═S)—*′,     -   R₁ to R₄ may each independently be deuterium, —F, —Cl, —Br, —I,         a hydroxyl group, a cyano group, a nitro group, an amino group,         an amidino group, a hydrazine group, a hydrazone group, a         carboxylic acid group or a salt thereof, a sulfonic acid group         or a salt thereof, a phosphoric acid group or a salt thereof, a         substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted         or unsubstituted C₂-C₆₀ alkenyl group, a substituted or         unsubstituted C₂-C₆₀ alkynyl group, a substituted or         unsubstituted C₁-C₆₀ alkoxy group, a substituted or         unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or         unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or         unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted         C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀         arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl         group, a substituted or unsubstituted monovalent non-aromatic         condensed polycyclic group, a substituted or unsubstituted         monovalent non-aromatic condensed heteropolycyclic group,         —C(Q₅)(Q₆)(Q₇), —Si(Q₅)(Q₆)(Q₇), —B(Q₅)(Q₆), —N(Q₅)(Q₆),         —P(Q₅)(Q₆), —C(═O)(Q₅), —S(═O)(Q₅), —S(═O)₂(Q₅), —P(═O)(Q₅)(Q₆),         or —P(═S)(Q₅)(Q₆),     -   neighboring groups among R₁ to R₄ and L₁ to L₃ may optionally be         bonded to each other to form a substituted or unsubstituted         C₅-C₆₀ carbocyclic group or a substituted or unsubstituted         C₁-C₆₀ heterocyclic group,     -   a1 to a3 may each independently be an integer from 0 to 3,     -   b1 to b4 may each independently be an integer from 0 to 10,     -   at least one of substituents of the substituted C₆-C₃₀ arylene         group, the substituted C₁-C₃₀ heteroarylene group, the         substituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀ alkenyl         group, the substituted C₂-C₆₀ alkynyl group, the substituted         C₁-C₆₀ alkoxy group, the substituted C₃-C₁₀ cycloalkyl group,         the substituted C₁-C₁₀ heterocycloalkyl group, the substituted         C₃-C₁₀ cycloalkenyl group, the substituted C₁-C₁₀         heterocycloalkenyl group, the substituted C₆-C₆₀ aryl group, the         substituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀         arylthio group, the substituted C₁-C₆₀ heteroaryl group, the         substituted monovalent non-aromatic condensed polycyclic group,         the substituted monovalent non-aromatic condensed         heteropolycyclic group, the substituted C₅-C₆₀ carbocyclic         group, and the substituted C₁-C₆₀ heterocyclic group may be:     -   deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amidino group, a hydrazino group, a hydrazono         group, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀         alkynyl group, or a C₁-C₆₀ alkoxy group;     -   a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl         group, or a C₁-C₆₀ alkoxy group, each substituted with         deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amidino group, a hydrazino group, a hydrazono         group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl         group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl         group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀         arylthio group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀         heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a monovalent         non-aromatic condensed polycyclic group, a monovalent         non-aromatic condensed heteropolycyclic group,         —Si(Q₁₁)(Q₁₂)(Q₁₃), —N(Q₁₁)(Q₁₂), —B(Q₁₁)(Q₁₂), —C(═O)(Q₁₁),         —S(═O)₂(Q₁₁), —P(═O)(Q₁₁)(Q₁₂), or any combination thereof;     -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio         group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group,         a C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic         condensed polycyclic group, or a monovalent non-aromatic         condensed heteropolycyclic group;     -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio         group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group,         a C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic         condensed polycyclic group, or a monovalent non-aromatic         condensed heteropolycyclic group, each substituted with         deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amidino group, a hydrazino group, a hydrazono         group, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀         alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group,         a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a         C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀         aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl         group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio         group, a monovalent non-aromatic condensed polycyclic group, a         monovalent non-aromatic condensed heteropolycyclic group,         —Si(Q₂₁)(Q₂₂)(Q₂₃), —N(Q₂₁)(Q₂₂), —B(Q₂₁)(Q₂₂), —C(═O)(Q₂₁),         —S(═O)₂(Q₂₁), —P(═O)(Q₂₁)(Q₂₂), or any combination thereof; or     -   —Si(Q₃₁)(Q₃₂)(Q₃₃), —N(Q₃₁)(Q₃₂), —B(Q₃₁)(Q₃₂), —C(═O)(Q₃₁),         —S(═O)₂(Q₃₁), or —P(═O)(Q₃₁)(Q₃₂), and     -   Q₁ to Q₇, Q₁₁ to Q₁₃, Q₂₁ to Q₂₃, and Q₃₁ to Q₃₃ may each         independently be hydrogen, deuterium, —F, —Cl, —Br, —I, a         hydroxyl group, a cyano group, a nitro group, an amidino group,         a hydrazino group, a hydrazono group, a C₁-C₆₀ alkyl group, a         C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy         group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl         group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl         group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀         arylthio group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀         heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a monovalent         non-aromatic condensed polycyclic group, a monovalent         non-aromatic condensed heteropolycyclic group, a biphenyl group,         or a terphenyl group.

In an embodiment, in Formula 3, one of CY₁ and CY₄ may be a carbene group.

In an embodiment, the third compound may be represented by Formula 3A:

In Formula 3A,

-   -   CY₁₃ and CY₁₄ may each independently be a benzene group, a         naphthalene group, an anthracene group, a phenanthrene group, a         triphenylene group, a pyrene group, a chrysene group, a         cyclopentadiene group, a 1,2,3,4-tetrahydronaphthalene group, a         carbene group, a thiophene group, a furan group, a selenophene         group, an indole group, a benzoborole group, a benzophosphole         group, an indene group, a benzosilole group, a benzogermole         group, a benzothiophene group, a benzoselenophene group, a         benzofuran group, a carbazole group, a dibenzoborole group, a         dibenzophosphole group, a fluorene group, a dibenzosilole group,         a dibenzogermole group, a dibenzothiophene group, a         dibenzoselenophene group, a dibenzofuran group, a         dibenzothiophene 5-oxide group, a 9H-fluorene-9-one group, a         dibenzothiophene 5,5-dioxide group, an azaindole group, an         azabenzoborole group, an azabenzophosphole group, an azaindene         group, an azabenzosilole group, an azabenzogermole group, an         azabenzothiophene group, an azabenzoselenophene group, an         azabenzofuran group, an azacarbazole group, an azadibenzoborole         group, an azadibenzophosphole group, an azafluorene group, an         azadibenzosilole group, an azadibenzogermole group, an         azadibenzothiophene group, an azadibenzoselenophene group, an         azadibenzofuran group, an azadibenzothiophene 5-oxide group, an         aza-9H-fluorene-9-one group, an azadibenzothiophene 5,5-dioxide         group, a pyridine group, a pyrimidine group, a pyrazine group, a         pyridazine group, a triazine group, a quinoline group, an         isoquinoline group, a quinoxaline group, a quinazoline group, a         phenanthroline group, a pyrrole group, a pyrazole group, an         imidazole group, a triazole group, an oxazole group, an         isooxazole group, a thiazole group, an isothiazole group, an         oxadiazole group, a thiadiazole group, a benzopyrazole group, a         benzimidazole group, a benzoxazole group, a benzothiazole group,         a benzoxadiazole group, a benzothiadiazole group, a         5,6,7,8-tetrahydroisoquinoline group, or a         5,6,7,8-tetrahydroquinoline group,     -   X₁₃ and X₁₄ may each independently be N or C,     -   L₁₂ and L₁₃ may each independently be a single bond, a double         bond, *—O—*′ *—S—*′, *—C(═O)—*′, *—S(═O)—*′, *—C(Q₁)(Q₂)-*′,         *—C(Q₁)=C(Q₂)-*′, *—C(Q₁)=*′, *—Si(Q₁)(Q₂)-*, *—B(Q₁)-*′,         *—N(Q₁)-*′, or *—P(Q₁)-*′,     -   T₁₁ to T₁₄ may each independently be a chemical bond, *—O—*′, or         *—S—*′,     -   a12 and a13 may each independently be an integer from 0 to 3,     -   b13 and b14 may each independently be an integer from 0 to 10,     -   R_(11a), R_(11b), R_(11c), R_(12a), R_(12b), R_(12c), R₁₃, and         R₁₄ may each independently be:     -   hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano         group, a nitro group, a C₁-C₂₀ alkyl group, or a C₁-C₂₀ alkoxy         group;     -   a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted         with deuterium, —F, —Cl, —Br, —I, a cyano group, a phenyl group,         a biphenyl group, or any combination thereof;     -   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a         cyclopentenyl group, a cyclohexenyl group, a phenyl group, a         biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl         group, a spiro-bifluorenyl group, a         spiro-fluorene-benzofluorenyl group, a benzofluorenyl group, a         dibenzofluorenyl group, a pyrenyl group, a phenalenyl group, a         phenanthrenyl group, an anthracenyl group, a fluoranthenyl         group, a triphenylenyl group, a pyrrolyl group, a thiophenyl         group, a furanyl group, a silolyl group, an imidazolyl group, a         pyrazolyl group, a thiazolyl group, an isothiazolyl group, an         oxazolyl group, an isoxazolyl group, a pyridinyl group, a         pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an         indolyl group, an isoindolyl group, an indazolyl group, a         purinyl group, a quinolinyl group, an isoquinolinyl group, a         benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl         group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl         group, a phenanthridinyl group, an acridinyl group, a         phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl         group, a benzofuranyl group, a benzothiophenyl group, a         benzosilolyl group, a benzoisothiazolyl group, a benzoxazolyl         group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl         group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl         group, a dibenzothiophenyl group, a dibenzosilolyl group, a         carbazolyl group, a benzocarbazolyl group, a dibenzocarbazolyl         group, a thiadiazolyl group, an imidazopyridinyl group, an         imidazopyrimidinyl group, an oxazolopyridinyl group, a         thiazolopyridinyl group, a benzonaphthyridinyl group, an         azafluorenyl group, an azaspiro-bifluorenyl group, an         azacarbazolyl group, an azadibenzofuranyl group, an         azadibenzothiophenyl group, an azadibenzosilolyl group,         —Si(Q₅)(Q₆)(Q₇), —N(Q₅)(Q₆), or —B(Q₅)(Q₆); or     -   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a         cyclopentenyl group, a cyclohexenyl group, a phenyl group, a         biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl         group, a spiro-bifluorenyl group, a         spiro-fluorene-benzofluorenyl group, a benzofluorenyl group, a         dibenzofluorenyl group, a pyrenyl group, a phenalenyl group, a         phenanthrenyl group, an anthracenyl group, a fluoranthenyl         group, a triphenylenyl group, a pyrrolyl group, a thiophenyl         group, a furanyl group, a silolyl group, an imidazolyl group, a         pyrazolyl group, a thiazolyl group, an isothiazolyl group, an         oxazolyl group, an isoxazolyl group, a pyridinyl group, a         pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an         indolyl group, an isoindolyl group, an indazolyl group, a         purinyl group, a quinolinyl group, an isoquinolinyl group, a         benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl         group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl         group, a phenanthridinyl group, an acridinyl group, a         phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl         group, a benzofuranyl group, a benzothiophenyl group, a         benzosilolyl group, a benzoisothiazolyl group, a benzoxazolyl         group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl         group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl         group, a dibenzothiophenyl group, a dibenzosilolyl group, a         carbazolyl group, a benzocarbazolyl group, a dibenzocarbazolyl         group, a thiadiazolyl group, an imidazopyridinyl group, an         imidazopyrimidinyl group, an oxazolopyridinyl group, a         thiazolopyridinyl group, a benzonaphthyridinyl group, an         azafluorenyl group, an azaspiro-bifluorenyl group, an         azacarbazolyl group, an azadibenzofuranyl group, an         azadibenzothiophenyl group, or an azadibenzosilolyl group, each         substituted with deuterium, —F, —Cl, —Br, —I, a hydroxyl group,         a cyano group, a nitro group, an amidino group, a hydrazino         group, a hydrazono group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy         group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl         group, a cyclopentenyl group, a cyclohexenyl group, a phenyl         group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl         group, a spiro-fluorene-benzofluorenyl group, a benzofluorenyl         group, a dibenzofluorenyl group, a pyrenyl group, a phenalenyl         group, a phenanthrenyl group, an anthracenyl group, a         fluoranthenyl group, a triphenylenyl group, a pyrrolyl group, a         thiophenyl group, a furanyl group, a silolyl group, an         imidazolyl group, a pyrazolyl group, a thiazolyl group, an         isothiazolyl group, an oxazolyl group, an isoxazolyl group, a         pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a         pyridazinyl group, an indolyl group, an isoindolyl group, an         indazolyl group, a purinyl group, a quinolinyl group, an         isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl         group, a naphthyridinyl group, a quinoxalinyl group, a         quinazolinyl group, a cinnolinyl group, a phenanthridinyl group,         an acridinyl group, a phenanthrolinyl group, a phenazinyl group,         a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl         group, a benzosilolyl group, a benzoisothiazolyl group, a         benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group,         a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a         dibenzofuranyl group, a dibenzothiophenyl group, a         dibenzosilolyl group, a carbazolyl group, a benzocarbazolyl         group, a dibenzocarbazolyl group, a thiadiazolyl group, an         imidazopyridinyl group, an imidazopyrimidinyl group, an         oxazolopyridinyl group, a thiazolopyridinyl group, a         benzonaphthyridinyl group, an azafluorenyl group, an         azaspiro-bifluorenyl group, an azacarbazolyl group, an         azadibenzofuranyl group, an azadibenzothiophenyl group, an         azadibenzosilolyl group, a biphenyl group, a terphenyl group, or         any combination thereof, and     -   Q₁, Q₂, and Q₅ to Q₇ may each independently be hydrogen,         deuterium, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl         group, a naphthyl group, a fluorenyl group, a carbazolyl group,         a dibenzofuranyl group, a dibenzothiophenyl group, a         triphenylenyl group, a biphenyl group, a terphenyl group, or a         tetraphenyl group.

In Formula 3A, neighboring groups among R_(11a), R_(11b), R_(11c), R_(12a), R_(12b), R_(12c), R₁₃, R₁₄, L₁₂, and L₁₃ may optionally be bonded to each other to form a substituted or unsubstituted C₅-C₆₀ carbocyclic group or a substituted or unsubstituted C₁-C₆₀ heterocyclic group.

In an embodiment, in Formula 3A, R_(11b) and R_(11c) may be bonded to each other to form a benzene ring, a naphthalene ring, a pyridine ring, a pyrimidine ring, or a pyrazine ring, each unsubstituted or substituted with at least one R_(a), and R_(a) may be the same as described herein.

In an embodiment, the third compound may include one of Compounds 3-1 to 3-6, but embodiments are not limited thereto:

[Fourth Compound]

In an embodiment, the halogen group of the fourth compound may be directly bonded to an iridium (Ir) atom.

In an embodiment, the fourth compound may be represented by Formula 4:

In Formula 4,

-   -   CY₅ and CY₆ may each independently be a C₅-C₃₀ carbocyclic group         or a C₁-C₃₀ heterocyclic group,     -   each L₅ may independently be a single bond, a double bond, a         substituted or unsubstituted C₆-C₃₀ arylene group, a substituted         or unsubstituted C₁-C₃₀ heteroarylene group, *—O—*′, *—S—*′,         *—C(═O)—*′, *—S(═O)—*′, *—C(Q₁)(Q₂)-*′, *—C(Q₁)=C(Q₂)-*′,         *—C(Q₁)=*′, *—Si(Q₁)(Q₂)-*′, *—B(Q₁)-*′, *—N(Q₁)-*′, or         *—P(Q₁)-*′,     -   T₇ may be a chemical bond, *—O—*′, *—S—*′, *—B(Q₃)-*′,         *—N(Q₃)-*′, *—P(Q₃)-*′, *—C(Q₃)(Q₄)-*, *—Si(Q₃)(Q₄)-*′,         *—Ge(Q₃)(Q₄)-*′, *—C(═O)—*′, or *—C(═S)—*′,     -   R₅ and R₆ may each independently be deuterium, —F, —Cl, —Br, —I,         a hydroxyl group, a cyano group, a nitro group, an amino group,         an amidino group, a hydrazine group, a hydrazone group, a         carboxylic acid group or a salt thereof, a sulfonic acid group         or a salt thereof, a phosphoric acid group or a salt thereof, a         substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted         or unsubstituted C₂-C₆₀ alkenyl group, a substituted or         unsubstituted C₂-C₆₀ alkynyl group, a substituted or         unsubstituted C₁-C₆₀ alkoxy group, a substituted or         unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or         unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or         unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted         C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀         arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl         group, a substituted or unsubstituted monovalent non-aromatic         condensed polycyclic group, a substituted or unsubstituted         monovalent non-aromatic condensed heteropolycyclic group,         —C(Q₅)(Q₆)(Q₇), —Si(Q₅)(Q₆)(Q₇), —B(Q₅)(Q₆), —N(Q₅)(Q₆),         —P(Q₅)(Q₆), —C(═O)(Q₅), —S(═O)(Q₅), —S(═O)₂(Q₅), —P(═O)(Q₅)(Q₆),         or —P(═S)(Q₅)(Q₆),     -   Y₇ may be a substituted or unsubstituted C₁-C₆₀ alkyl group, a         substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted         or unsubstituted C₂-C₆₀ alkynyl group, a substituted or         unsubstituted C₁-C₆₀ alkoxy group, a substituted or         unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or         unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or         unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted         C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀         arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl         group, a substituted or unsubstituted monovalent non-aromatic         condensed polycyclic group, a substituted or unsubstituted         monovalent non-aromatic condensed heteropolycyclic group,         —C(Q₈)(Q₉)(Q₁₀), —Si(Q₈)(Q₉)(Q₁₀), —B(Q₈)(Q₉), —N(Q₈)(Q₉),         —P(Q₈)(Q₉), —C(═O)(Q₈), —S(═O)(Q₈), —S(═O)₂(Q₈), —P(═O)(Q₈)(Q₉),         or —P(═S)(Q₈)(Q₉),     -   Q₁ to Q₁ o may each independently be hydrogen, deuterium, —F,         —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amidino group, a hydrazino group, a hydrazono group, a C₁-C₆₀         alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a         C₁-C₆ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀         heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀         heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy         group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a         C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a         monovalent non-aromatic condensed polycyclic group, a monovalent         non-aromatic condensed heteropolycyclic group, a biphenyl group,         or a terphenyl group,     -   a5 may be an integer from 0 to 3,     -   b5 and b6 may each independently be an integer from 0 to 10,     -   c7 may be 0, 1, 2, or 3,     -   d7 may be 1, 2, or 3, and     -   X may be F, Cl, or I.

In an embodiment, in Formula 4,

-   -   CY₅ and CY₆ may each independently be a benzene group, a         naphthalene group, an anthracene group, a phenanthrene group, a         triphenylene group, a pyrene group, a chrysene group, a         cyclopentadiene group, a 1,2,3,4-tetrahydronaphthalene group, a         carbene group, a thiophene group, a furan group, a selenophene         group, an indole group, a benzoborole group, a benzophosphole         group, an indene group, a benzosilole group, a benzogermole         group, a benzothiophene group, a benzoselenophene group, a         benzofuran group, a carbazole group, a dibenzoborole group, a         dibenzophosphole group, a fluorene group, a dibenzosilole group,         a dibenzogermole group, a dibenzothiophene group, a         dibenzoselenophene group, a dibenzofuran group, a         dibenzothiophene 5-oxide group, a 9H-fluorene-9-one group, a         dibenzothiophene 5,5-dioxide group, an azaindole group, an         azabenzoborole group, an azabenzophosphole group, an azaindene         group, an azabenzosilole group, an azabenzogermole group, an         azabenzothiophene group, an azabenzoselenophene group, an         azabenzofuran group, an azacarbazole group, an azadibenzoborole         group, an azadibenzophosphole group, an azafluorene group, an         azadibenzosilole group, an azadibenzogermole group, an         azadibenzothiophene group, an azadibenzoselenophene group, an         azadibenzofuran group, an azadibenzothiophene 5-oxide group, an         aza-9H-fluorene-9-one group, an azadibenzothiophene 5,5-dioxide         group, a pyridine group, a pyrimidine group, a pyrazine group, a         pyridazine group, a triazine group, a quinoline group, an         isoquinoline group, a quinoxaline group, a quinazoline group, a         phenanthroline group, a pyrrole group, a pyrazole group, an         imidazole group, a triazole group, an oxazole group, an         isooxazole group, a thiazole group, an isothiazole group, an         oxadiazole group, a thiadiazole group, a benzopyrazole group, a         benzimidazole group, a benzoxazole group, a benzothiazole group,         a benzoxadiazole group, a benzothiadiazole group, a         5,6,7,8-tetrahydroisoquinoline group, or a         5,6,7,8-tetrahydroquinoline group,     -   T₇ may be a chemical bond, *—O—*′, or *—S—*′,     -   L₅ is a single bond, and     -   Y₇ may be a substituted or unsubstituted C₂-C₂₀ alkenyl group, a         substituted or unsubstituted C₆-C₂₀ aryl group, a substituted or         unsubstituted C₂-C₂₀ heteroaryl group, a substituted or         unsubstituted monovalent non-aromatic condensed polycyclic         group, or a substituted or unsubstituted monovalent non-aromatic         condensed heteropolycyclic group.

In an embodiment, the fourth compound may be an organometallic compound represented by Formula 4A:

In Formula 4A,

-   -   CY₁₅ and CY₁₆ may each independently be a benzene group, a         naphthalene group, an anthracene group, a phenanthrene group, a         triphenylene group, a pyrene group, a chrysene group, a         cyclopentadiene group, a 1,2,3,4-tetrahydronaphthalene group, a         carbene group, a thiophene group, a furan group, a selenophene         group, an indole group, a benzoborole group, a benzophosphole         group, an indene group, a benzosilole group, a benzogermole         group, a benzothiophene group, a benzoselenophene group, a         benzofuran group, a carbazole group, a dibenzoborole group, a         dibenzophosphole group, a fluorene group, a dibenzosilole group,         a dibenzogermole group, a dibenzothiophene group, a         dibenzoselenophene group, a dibenzofuran group, a         dibenzothiophene 5-oxide group, a 9H-fluorene-9-one group, a         dibenzothiophene 5,5-dioxide group, an azaindole group, an         azabenzoborole group, an azabenzophosphole group, an azaindene         group, an azabenzosilole group, an azabenzogermole group, an         azabenzothiophene group, an azabenzoselenophene group, an         azabenzofuran group, an azacarbazole group, an azadibenzoborole         group, an azadibenzophosphole group, an azafluorene group, an         azadibenzosilole group, an azadibenzogermole group, an         azadibenzothiophene group, an azadibenzoselenophene group, an         azadibenzofuran group, an azadibenzothiophene 5-oxide group, an         aza-9H-fluorene-9-one group, an azadibenzothiophene 5,5-dioxide         group, a pyridine group, a pyrimidine group, a pyrazine group, a         pyridazine group, a triazine group, a quinoline group, an         isoquinoline group, a quinoxaline group, a quinazoline group, a         phenanthroline group, a pyrrole group, a pyrazole group, an         imidazole group, a triazole group, an oxazole group, an         isooxazole group, a thiazole group, an isothiazole group, an         oxadiazole group, a thiadiazole group, a benzopyrazole group, a         benzimidazole group, a benzoxazole group, a benzothiazole group,         a benzoxadiazole group, a benzothiadiazole group, a         5,6,7,8-tetrahydroisoquinoline group, or a         5,6,7,8-tetrahydroquinoline group,     -   X₁₅ and X₁₆ may each independently be N or C,     -   T₁₇ may be a chemical bond, *—O—*′, or *—S—*′,     -   Y₁₇ may be a substituted or unsubstituted C₂-C₂₀ alkenyl group,         a substituted or unsubstituted C₆-C₂₀ aryl group, a substituted         or unsubstituted C₂-C₂₀ heteroaryl group, a substituted or         unsubstituted monovalent non-aromatic condensed polycyclic         group, or a substituted or unsubstituted monovalent non-aromatic         condensed heteropolycyclic group,     -   R₁₅ and R₁₆ may each independently be:     -   hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano         group, a nitro group, a C₁-C₂₀ alkyl group, or a C₁-C₂₀ alkoxy         group;     -   a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted         with deuterium, —F, —Cl, —Br, —I, a cyano group, a phenyl group,         a biphenyl group, or any combination thereof;     -   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a         cyclopentenyl group, a cyclohexenyl group, a phenyl group, a         biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl         group, a spiro-bifluorenyl group, a         spiro-fluorene-benzofluorenyl group, a benzofluorenyl group, a         dibenzofluorenyl group, a pyrenyl group, a phenalenyl group, a         phenanthrenyl group, an anthracenyl group, a fluoranthenyl         group, a triphenylenyl group, a pyrrolyl group, a thiophenyl         group, a furanyl group, a silolyl group, an imidazolyl group, a         pyrazolyl group, a thiazolyl group, an isothiazolyl group, an         oxazolyl group, an isoxazolyl group, a pyridinyl group, a         pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an         indolyl group, an isoindolyl group, an indazolyl group, a         purinyl group, a quinolinyl group, an isoquinolinyl group, a         benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl         group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl         group, a phenanthridinyl group, an acridinyl group, a         phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl         group, a benzofuranyl group, a benzothiophenyl group, a         benzosilolyl group, a benzoisothiazolyl group, a benzoxazolyl         group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl         group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl         group, a dibenzothiophenyl group, a dibenzosilolyl group, a         carbazolyl group, a benzocarbazolyl group, a dibenzocarbazolyl         group, a thiadiazolyl group, an imidazopyridinyl group, an         imidazopyrimidinyl group, an oxazolopyridinyl group, a         thiazolopyridinyl group, a benzonaphthyridinyl group, an         azafluorenyl group, an azaspiro-bifluorenyl group, an         azacarbazolyl group, an azadibenzofuranyl group, an         azadibenzothiophenyl group, an azadibenzosilolyl group,         —Si(Q₅)(Q₆)(Q₇), —N(Q₅)(Q₆), or —B(Q₅)(Q₆); or     -   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a         cyclopentenyl group, a cyclohexenyl group, a phenyl group, a         biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl         group, a spiro-bifluorenyl group, a         spiro-fluorene-benzofluorenyl group, a benzofluorenyl group, a         dibenzofluorenyl group, a pyrenyl group, a phenalenyl group, a         phenanthrenyl group, an anthracenyl group, a fluoranthenyl         group, a triphenylenyl group, a pyrrolyl group, a thiophenyl         group, a furanyl group, a silolyl group, an imidazolyl group, a         pyrazolyl group, a thiazolyl group, an isothiazolyl group, an         oxazolyl group, an isoxazolyl group, a pyridinyl group, a         pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an         indolyl group, an isoindolyl group, an indazolyl group, a         purinyl group, a quinolinyl group, an isoquinolinyl group, a         benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl         group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl         group, a phenanthridinyl group, an acridinyl group, a         phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl         group, a benzofuranyl group, a benzothiophenyl group, a         benzosilolyl group, a benzoisothiazolyl group, a benzoxazolyl         group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl         group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl         group, a dibenzothiophenyl group, a dibenzosilolyl group, a         carbazolyl group, a benzocarbazolyl group, a dibenzocarbazolyl         group, a thiadiazolyl group, an imidazopyridinyl group, an         imidazopyrimidinyl group, an oxazolopyridinyl group, a         thiazolopyridinyl group, a benzonaphthyridinyl group, an         azafluorenyl group, an azaspiro-bifluorenyl group, an         azacarbazolyl group, an azadibenzofuranyl group, an         azadibenzothiophenyl group, or an azadibenzosilolyl group, each         substituted with deuterium, —F, —Cl, —Br, —I, a hydroxyl group,         a cyano group, a nitro group, an amidino group, a hydrazino         group, a hydrazono group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy         group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl         group, a cyclopentenyl group, a cyclohexenyl group, a phenyl         group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl         group, a spiro-fluorene-benzofluorenyl group, a benzofluorenyl         group, a dibenzofluorenyl group, a pyrenyl group, a phenalenyl         group, a phenanthrenyl group, an anthracenyl group, a         fluoranthenyl group, a triphenylenyl group, a pyrrolyl group, a         thiophenyl group, a furanyl group, a silolyl group, an         imidazolyl group, a pyrazolyl group, a thiazolyl group, an         isothiazolyl group, an oxazolyl group, an isoxazolyl group, a         pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a         pyridazinyl group, an indolyl group, an isoindolyl group, an         indazolyl group, a purinyl group, a quinolinyl group, an         isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl         group, a naphthyridinyl group, a quinoxalinyl group, a         quinazolinyl group, a cinnolinyl group, a phenanthridinyl group,         an acridinyl group, a phenanthrolinyl group, a phenazinyl group,         a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl         group, a benzosilolyl group, a benzoisothiazolyl group, a         benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group,         a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a         dibenzofuranyl group, a dibenzothiophenyl group, a         dibenzosilolyl group, a carbazolyl group, a benzocarbazolyl         group, a dibenzocarbazolyl group, a thiadiazolyl group, an         imidazopyridinyl group, an imidazopyrimidinyl group, an         oxazolopyridinyl group, a thiazolopyridinyl group, a         benzonaphthyridinyl group, an azafluorenyl group, an         azaspiro-bifluorenyl group, an azacarbazolyl group, an         azadibenzofuranyl group, an azadibenzothiophenyl group, an         azadibenzosilolyl group, a biphenyl group, a terphenyl group, or         any combination thereof,     -   Q₅ to Q₇ may each independently be hydrogen, deuterium, a C₁-C₁₀         alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, a naphthyl         group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl         group, a dibenzothiophenyl group, a triphenylenyl group, a         biphenyl group, a terphenyl group, or a tetraphenyl group,     -   neighboring groups among R₁₅ and R₁₆ may optionally bonded to         each other to form a substituted or unsubstituted C₅-C₆₀         carbocyclic group or a substituted or unsubstituted C₁-C₆₀         heterocyclic group,     -   b15 and b16 may each independently be an integer from 0 to 10,     -   c17 may be 0, 1, 2, or 3,     -   d17 may be 1, 2, or 3, and     -   X may be F, Cl, or I.

In an embodiment, the fourth compound may include one of Compounds 4-1 to 4-30, but embodiments are not limited thereto:

The fourth compound may assist emission of the third compound, as a sensitizer. For example, the fourth compound may assist the third compound to emit light by receiving excitons from the host and transmitting the excitons to the third compound.

When the fourth compound is an iridium (Ir) complex that includes a halogen group that is directly bonded to an Ir atom, spin orbit coupling (SOC) may increase, thereby increasing emission efficiency.

In an embodiment, an emission peak wavelength of an emission spectrum of the third compound may be greater than an emission peak wavelength of an emission spectrum of the fourth compound. Energy may be transferred from the fourth compound to the third compound, and the final light-emitting material of the emission layer may be the third compound.

In an embodiment, a ratio of emission components emitted from the third compound to total emission components emitted from the emission layer may be greater than or equal to about 80%.

In an embodiment, an emission peak wavelength of the emission layer may be in a range of about 430 nm to about 480 nm. For example, the emission layer may emit blue light.

[Fifth Compound]

In an embodiment, the emission layer may further include a fifth compound, wherein the fifth compound may be a fluorescent dopant, a delayed fluorescence dopant, or any combination thereof. When the emission layer further includes the fifth compound, the final light-emitting material may be the fifth compound.

In an embodiment, a ratio of emission components emitted from the fifth compound to total emission components emitted from the emission layer may be greater than or equal to about 80%. In an embodiment, an emission peak wavelength of an emission spectrum of the fifth compound may be greater than an emission peak wavelength of an emission spectrum of the fourth compound.

In an embodiment, an emission peak wavelength of the emission layer may be in a range of about 430 nm to about 480 nm. For example, the emission layer may emit blue light.

In an embodiment, the fifth compound may include a compound represented by Formula 5, a compound represented by Formula 6, a compound represented by Formula 7, or any combination thereof:

In Formula 5,

-   -   Ar₅₃ may be a substituted or unsubstituted C₅-C₆₀ carbocyclic         group or a substituted or unsubstituted C₁-C₆₀ heterocyclic         group,     -   L₅₁ to L₅₃ may each independently be a substituted or         unsubstituted C₃-C₁₀ cycloalkylene group, a substituted or         unsubstituted C₁-C₁₀heterocycloalkylene group, a substituted or         unsubstituted C₃-C₁₀ cycloalkenylene group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkenylene group, a substituted         or unsubstituted C₆-C₆₀ arylene group, a substituted or         unsubstituted C₁-C₆₀ heteroarylene group, a substituted or         unsubstituted divalent non-aromatic condensed polycyclic group,         or a substituted or unsubstituted divalent non-aromatic         condensed heteropolycyclic group,     -   a51 to a53 may each independently be an integer from 0 to 3,     -   R₅₁ and R₅₂ may each independently be a substituted or         unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or         unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or         unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted         C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀         arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl         group, a substituted or unsubstituted monovalent non-aromatic         condensed polycyclic group, or a substituted or unsubstituted         monovalent non-aromatic condensed heteropolycyclic group, and     -   n5 may be an integer from 1 to 6.

In an embodiment, in Formula 5, Ar₅₃ may include a condensed cyclic group (for example, an anthracene group, a chrysene group, a pyrene group, and the like) in which three or more monocyclic groups are condensed together.

In an embodiment, in Formula 5, n5 may be 2.

In Formula 6,

-   -   A₆₁ to A₆₃ may each independently be a C₃-C₆₀ carbocyclic group         or a C₁-C₆₀ heterocyclic group,     -   X₆₁ may be C(R₆₄)(R₆₅), N(R₆₄), O, or S,     -   X₆₂ may be C(R₆₆)(R₆₇), N(R₆₆), O, or S,     -   L₆₁ to L₆₃ may each independently be a C₃-C₆₀ carbocyclic group         that is unsubstituted or substituted with at least one R_(a) or         a C₁-C₆₀ heterocyclic group that is unsubstituted or substituted         with at least one R_(a),     -   a61 to a63 may each independently be an integer from 0 to 5,     -   R₆₁ to R₆₇ may each independently be hydrogen, deuterium, —F,         —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, a         C₁-C₆₀ alkyl group that is unsubstituted or substituted with at         least one R_(a), a C₂-C₆₀ alkenyl group that is unsubstituted or         substituted with at least one R_(a), a C₂-C₆₀ alkynyl group that         is unsubstituted or substituted with at least one R_(a), a         C₁-C₆₀ alkoxy group that is unsubstituted or substituted with at         least one R_(a), a C₃-C₆₀ carbocyclic group that is         unsubstituted or substituted with at least one R_(a), a C₁-C₆₀         heterocyclic group that is unsubstituted or substituted with at         least one R_(a), a C₆-C₆₀ aryloxy group that is unsubstituted or         substituted with at least one R_(a), a C₆-C₆₀ arylthio group         that is unsubstituted or substituted with at least one R_(a),         —Si(Q₁)(Q₂)(Q₃), —N(Q₁)(Q₂), —B(Q₁)(Q₂), —C(═O)(Q₁),         —S(═O)₂(Q₁), or —P(═O)(Q₁)(Q₂), and     -   b61 to b63 and n61 to n63 may each independently be an integer         from 1 to 5.

In Formula 6, R_(a) and Q₁ to Q₃ may each be the same as described in the specification.

In an embodiment, the fifth compound may include a compound represented by Formula 6A:

In Formula 6A,

-   -   R₆₁₁ to R₆₁₄ may each independently be the same as described in         connection with R₆₁ in Formula 6, R₆₂₁ to R₆₂₄ may each         independently be the same as described in connection with R₆₂ in         Formula 6, and R₆₃₁ to R₆₃₃ may each independently be the same         as described in connection with R₆₃ in Formula 6, and     -   X₆₁ and X₆₂ may each be the same as described in Formula 6.

In Formula 7,

R₇₁ to R₇₅ may each independently be hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, a C₁-C₆₀ alkyl group that is unsubstituted or substituted with at least one R_(a), a C₂-C₆₀ alkenyl group that is unsubstituted or substituted with at least one R_(a), a C₂-C₆₀ alkynyl group that is unsubstituted or substituted with at least one R_(a), a C₁-C₆₀ alkoxy group that is unsubstituted or substituted with at least one R_(a), a C₃-C₆₀ carbocyclic group that is unsubstituted or substituted with at least one R_(a), a C₁-C₆₀ heterocyclic group that is unsubstituted or substituted with at least one R_(a), a C₆-C₆₀ aryloxy group that is unsubstituted or substituted with at least one R_(a), a C₆-C₆₀ arylthio group that is unsubstituted or substituted with at least one R_(a), —Si(Q₁)(Q₂)(Q₃), —N(Q₁)(Q₂), —B(Q₁)(Q₂), —C(═O)(Q₁), —S(═O)₂(Q₁), or —P(═O)(Q₁)(Q₂), and

-   -   b73 may be an integer from 0 to 4, b74 may be an integer from 0         to 4, and b75 may be an integer from 0 to 6.

In Formula 7, R_(a) and Q₁ to Q₃ may each be the same as described in the specification.

In an embodiment, the compound represented by Formula 5 may include at least one of Compounds 5-1 to 5-4, the compound represented by Formula 6 may include at least one of Compounds 6-1 to 6-4, and the compound represented by Formula 7 may include at least one of Compounds 7-1 and 7-2:

[Electron Transport Region in Interlayer 130]

The electron transport region may have a structure consisting of a layer consisting of a single material, a structure consisting of a layer including different materials, or a structure including multiple layers including different materials.

The electron transport region may include a buffer layer, a hole blocking layer, an electron control layer, an electron transport layer, an electron injection layer, or any combination thereof, but embodiments are not limited thereto.

In an embodiment, the electron transport region may have an electron transport layer/electron injection layer structure, a hole blocking layer/electron transport layer/electron injection layer structure, an electron control layer/electron transport layer/electron injection layer structure, or a buffer layer/electron transport layer/electron injection layer structure, wherein the layers of each structure may be stacked from an emission layer in its respective stated order. However, embodiments are not limited thereto.

The electron transport region (for example, a buffer layer, a hole blocking layer, an electron control layer, or an electron transport layer in the electron transport region) may include a metal-free compound containing at least one π electron-deficient nitrogen-containing ring.

The term “π electron-deficient nitrogen-containing ring” as used herein may be a C₁-C₆₀ heterocyclic group and may include at least one *—N═*′ moiety as a ring-forming moiety.

For example, a “π electron-deficient nitrogen-containing ring” may be: a 5-membered to 7-membered heteromonocyclic group having at least one *—N═*′ moiety; a heteropolycyclic group in which two or more 5-membered to 7-membered heteromonocyclic groups each having at least one *—N═*′ moiety are condensed with each other; or a heteropolycyclic group in which at least one of 5-membered to 7-membered heteromonocyclic groups, each having at least one *—N═*′ moiety, is condensed with at least one C₅-C₆₀ carbocyclic group.

Examples of the π electron-deficient nitrogen-containing ring may include an imidazole ring, a pyrazole ring, a thiazole ring, an isothiazole ring, an oxazole ring, an isoxazole ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, an indazole ring, a purine ring, a quinoline ring, an isoquinoline ring, a benzoquinoline ring, a phthalazine ring, a naphthyridine ring, a quinoxaline ring, a quinazoline ring, a cinnoline ring, a phenanthridine ring, an acridine ring, a phenanthroline ring, a phenazine ring, a benzimidazole ring, an isobenzothiazole ring, a benzoxazole ring, an isobenzoxazole ring, a triazole ring, a tetrazole ring, an oxadiazole ring, a triazine ring, a thiadiazole ring, an imidazopyridine ring, an imidazopyrimidine ring, and an azacarbazole ring, but are not limited thereto.

In an embodiment, the electron transport region may include a compound represented by Formula 601.

[Ar₆₀₁]_(xe11)-[(L₆₀₁)_(xe1)-R₆₀₁]_(xe21)  [Formula 601]

In Formula 601,

-   -   Ar₆₀₁ and L₆₀₁ may each independently be a C₃-C₆₀ carbocyclic         group that is unsubstituted or substituted with at least one         R_(a) or a C₁-C₆₀ heterocyclic group that is unsubstituted or         substituted with at least one R_(a),     -   xe11 may be 1, 2, or 3,     -   xe1 may be 0, 1, 2, 3, 4, or 5,     -   R₆₀₁ may be C₃-C₆₀ carbocyclic group that is unsubstituted or         substituted with at least one R_(a), a C₁-C₆₀ heterocyclic group         that is unsubstituted or substituted with at least one R_(a),         —Si(Q₆₀₁)(Q₆₀₂)(Q₆₀₃), —C(═O)(Q₆₀₁), —S(═O)₂(Q₆₀₁), or         —P(═O)(Q₆₀₁)(Q₆₀₂),     -   Q₆₀₁ to Q₆₀₃ may each independently be the same as described in         connection with Q₁,     -   xe21 may be 1, 2, 3, 4, or 5, and     -   at least one of Ar₆₀₁, L₆₀₁, and R₆₀₁ may each independently be         a π electron-deficient nitrogen-containing C₁-C₆₀ cyclic group         that is unsubstituted or substituted with at least one R_(a).

In an embodiment, in Formula 601, when xe11 is 2 or more, two or more Ar₆₀₁(s) may be linked to each other via a single bond.

In an embodiment, in Formula 601, Ar₆₀₁ may be a substituted or unsubstituted anthracene group.

In an embodiment, the electron transport region may include a compound represented by Formula 601-1:

In Formula 601-1,

-   -   X₆₁₄ may be N or C(R₆₁₄), X₆₁₅ may be N or C(R₆₁₅), X₆₁₆ may be         N or C(R₆₁₆), and at least one of X₆₁₄ to X₆₁₆ may each be N,     -   L₆₁₁ to L₆₁₃ may each independently be the same as described in         connection with L₆₀₁,     -   xe611 to xe613 may each independently be the same as described         in connection with xe1,     -   R₆₁₁ to R₆₁₃ may each independently be the same as described in         connection with R₆₀₁, and     -   R₆₁₄ to R₆₁₆ may each independently be hydrogen, deuterium, —F,         —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, a         C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a C₃-C₆₀ carbocyclic         group that is unsubstituted or substituted with at least one         R_(a), or a C₁-C₆₀ heterocyclic group that is unsubstituted or         substituted with at least one R_(a).

In an embodiment, in Formulae 601 and 601-1, xe1 and xe611 to xe613 may each independently be 0, 1, or 2.

The electron transport region may include one of Compounds ET1 to ET46, 2,9-dimethyl-4,7-diphenyl-1, 10-phenanthroline (BCP), 4,7-diphenyl-1,10-phenanthroline (Bphen), Alq₃, BAIq, TAZ, NTAZ, or any combination thereof:

A thickness of the electron transport region may be in a range of about 160 Å to about 5,000 Å. For example, the thickness of the electron transport region may be in a range of about 100 Å to about 4,000 Å. When the electron transport region includes a buffer layer, a hole blocking layer, an electron control layer, an electron transport layer, or any combination thereof, a thickness of the buffer layer, the hole blocking layer, or the electron control layer may each independently be in a range of about 20 Å to about 1,000 Å, and a thickness of the electron transport layer may be in a range of about 100 Å to about 1,000 Å. For example, the thickness of the buffer layer, the hole blocking layer, or the electron control layer may each independently be in a range of about 30 Å to about 300 Å. For example, thickness of the electron transport layer may be in a range of about 150 Å to about 500 Å. When the thicknesses of the buffer layer, the hole blocking layer, the electron control layer, the electron transport layer, and/or the electron transport region are within these ranges, satisfactory electron-transporting characteristics may be obtained without a substantial increase in driving voltage.

The electron transport region (for example, an electron transport layer in the electron transport region) may further include, in addition to the materials described above, a metal-containing material.

The metal-containing material may include an alkali metal complex, an alkaline earth metal complex, or any combination thereof. A metal ion of the alkali metal complex may be a Li ion, a Na ion, a K ion, a Rb ion, or a Cs ion, and a metal ion of the alkaline earth metal complex may be a Be ion, a Mg ion, a Ca ion, a Sr ion, or a Ba ion.

A ligand coordinated with the metal ion of the alkali metal complex or with the metal ion of the alkaline earth-metal complex may each independently include a hydroxyquinoline, a hydroxyisoquinoline, a hydroxybenzoquinoline, a hydroxyacridine, a hydroxyphenanthridine, a hydroxyphenyloxazole, a hydroxyphenylthiazole, a hydroxydiphenyloxadiazole, a hydroxydiphenylthiadiazole, a hydroxyphenylpyridine, a hydroxyphenylbenzimidazole, a hydroxyphenylbenzothiazole, a bipyridine, a phenanthroline, a cyclopentadiene, or any combination thereof.

In an embodiment, the metal-containing material may include a lithium (Li) complex. The Li complex may include, for example, Compound ET-D1 (LiQ) or Compound ET-D2:

The electron transport region may include an electron injection layer to facilitate the injection of electrons from the second electrode 150. The electron injection layer may directly contact the second electrode 150.

The electron injection layer may have a structure consisting of a layer consisting of a single material, a structure consisting of a layer including different materials, or a structure including multiple layers including different materials.

The electron injection layer may include an alkali metal, an alkaline earth metal, a rare earth metal, an alkali metal-containing compound, an alkaline earth metal-containing compound, a rare earth metal-containing compound, an alkali metal complex, an alkaline earth metal complex, a rare earth metal complex, or any combination thereof.

The alkali metal may include Li, Na, K, Rb, Cs, or any combination thereof. The alkaline earth metal may include Mg, Ca, Sr, Ba, or any combination thereof. The rare earth metal may include Sc, Y, Ce, Tb, Yb, Gd, or any combination thereof.

The alkali metal-containing compound, the alkaline earth metal-containing compound, and the rare earth metal-containing compound may include oxides, halides (for example, fluorides, chlorides, bromides, or iodides), or tellurides of the alkali metal, the alkaline earth metal, and the rare earth metal, or any combination thereof.

The alkali metal-containing compound may include: alkali metal oxides, such as Li₂O, Cs₂O, or K₂O; alkali metal halides, such as LiF, NaF, CsF, KF, LiI, NaI, CsI, or KI; or any combination thereof. The alkaline earth metal-containing compound may include an alkaline earth metal compound, such as BaO, SrO, CaO, Ba_(x)Sr_(1-x)O (x is a real number satisfying the condition of 0<x<1), Ba_(x)Ca_(1-x)O (x is a real number satisfying the condition of 0<x<1), or the like. The rare earth metal-containing compound may include YbF₃, ScF₃, Sc₂O₃, Y₂O₃, Ce₂O₃, GdF₃, TbF₃, YbI₃, ScI₃, TbI₃, or any combination thereof. In an embodiment, the rare earth metal-containing compound may include a lanthanide metal telluride. Examples of the lanthanide metal telluride may include LaTe, CeTe, PrTe, NdTe, PmTe, SmTe, EuTe, GdTe, TbTe, DyTe, HoTe, ErTe, TmTe, YbTe, LuTe, La₂Te₃, Ce₂Te₃, Pr₂Te₃, Nd₂Te₃, Pm₂Te₃, Sm₂Te₃, Eu₂Te₃, Gd₂Te₃, Tb₂Te₃, Dy₂Te₃, Ho₂Te₃, Er₂Te₃, Tm₂Te₃, Yb₂Te₃, and Lu₂Te₃.

The alkali metal complex, the alkaline earth-metal complex, and the rare earth metal complex may include one of an alkali metal ion, an alkaline earth metal ion, and a rare earth metal ion, and a ligand bonded to the metal ion (for example, a hydroxyquinoline, a hydroxyisoquinoline, a hydroxybenzoquinoline, a hydroxyacridine, a hydroxyphenanthridine, a hydroxyphenyloxazole, a hydroxyphenylthiazole, a hydroxydiphenyloxadiazole, a hydroxydiphenylthiadiazole, a hydroxyphenylpyridine, a hydroxyphenyl benzimidazole, a hydroxyphenylbenzothiazole, a bipyridine, a phenanthroline, a cyclopentadiene, or any combination thereof).

The electron injection layer may consist of an alkali metal, an alkaline earth metal, a rare earth metal, an alkali metal-containing compound, an alkaline earth metal-containing compound, a rare earth metal-containing compound, an alkali metal complex, an alkaline earth metal complex, a rare earth metal complex, or any combination thereof, as described above. In an embodiment, the electron injection layer may further include an organic material (for example, a compound represented by Formula 601).

In an embodiment, the electron injection layer may consist of an alkali metal-containing compound (for example, an alkali metal halide); or the electron injection layer may consist of an alkali metal-containing compound (for example, an alkali metal halide), and an alkali metal, an alkaline earth metal, a rare earth metal, or any combination thereof. In an embodiment, the electron injection layer may be a KI:Yb co-deposited layer, a RbI:Yb co-deposited layer, or the like.

When the electron injection layer further includes an organic material, an alkali metal, an alkaline earth metal, a rare earth metal, an alkali metal-containing compound, an alkaline earth metal-containing compound, a rare earth metal-containing compound, an alkali metal complex, an alkaline earth-metal complex, a rare earth metal complex, or any combination thereof may be homogeneously or non-homogeneously dispersed in a matrix including the organic material.

A thickness of the electron injection layer may be in a range of about 1 Å to about 100 Å. For example, the thickness of the electron injection layer may be in a range of about 3 Å to about 90 Å. When the thickness of the electron injection layer is within the range described above, satisfactory electron injection characteristics may be obtained without a substantial increase in driving voltage.

[Second Electrode 150]

The second electrode 150 may be located on the interlayer 130 having such a structure. The second electrode 150 may be a cathode, which is an electron injection electrode. A material for forming the second electrode 150 may be a material having a low work function, for example, a metal, an alloy, an electrically conductive compound, or any combination thereof.

In an embodiment, the second electrode 150 may include lithium (Li), silver (Ag), magnesium (Mg), aluminum (AI), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), magnesium-silver (Mg—Ag), ytterbium (Yb), silver-ytterbium (Ag—Yb), ITO, IZO, or any combination thereof. The second electrode 150 may be a transmissive electrode, a semi-transmissive electrode, or a reflective electrode.

The second electrode 150 may have a single-layered structure or a multilayer structure.

[Capping Layer]

The light-emitting device 10 may include a first capping layer located outside the first electrode 110, and/or a second capping layer located outside the second electrode 150. For example, the light-emitting device 10 may have a structure in which the first capping layer, the first electrode 110, the interlayer 130, and the second electrode 150 are stacked in this stated order, a structure in which the first electrode 110, the interlayer 130, the second electrode 150, and the second capping layer are stacked in this stated order, or a structure in which the first capping layer, the first electrode 110, the interlayer 130, the second electrode 150, and the second capping layer are stacked in this stated order.

Light generated in an emission layer of the interlayer 130 of the light-emitting device 10 may be extracted toward the outside through the first electrode 110, which may be a semi-transmissive electrode or a transmissive electrode, and through the first capping layer. Light generated in an emission layer of the interlayer 130 of the light-emitting device 10 may be extracted toward the outside through the second electrode 150, which may be a semi-transmissive electrode or a transmissive electrode, and through the second capping layer.

The first capping layer and the second capping layer may each increase external emission efficiency according to the principle of constructive interference. Accordingly, the light extraction efficiency of the light-emitting device 10 is increased, so that the emission efficiency of the light-emitting device 10 may be improved.

The first capping layer and the second capping layer may each include a material having a refractive index equal to or greater than about 1.6 (with respect to a wavelength of about 589 nm).

The first capping layer and the second capping layer may each independently be an organic capping layer including an organic material, an inorganic capping layer including an inorganic material, or an organic-inorganic composite capping layer including an organic material and an inorganic material.

At least one of the first capping layer and the second capping layer may each independently include carbocyclic compounds, heterocyclic compounds, amine group-containing compounds, porphyrin derivatives, phthalocyanine derivatives, naphthalocyanine derivatives, alkali metal complexes, alkaline earth metal complexes, or any combination thereof. The carbocyclic compound, the heterocyclic compound, and the amine group-containing compound may be optionally substituted with a substituent containing O, N, S, Se, Si, F, Cl, Br, I, or any combination thereof.

In an embodiment, at least one of the first capping layer and the second capping layer may each independently include an amine group-containing compound.

In an embodiment, at least one of the first capping layer and the second capping layer may each independently include a compound represented by Formula 201, a compound represented by Formula 202, or any combination thereof.

In an embodiment, at least one of the first capping layer and the second capping layer may each independently include one of Compounds HT28 to HT33, one of Compounds CP1 to CP6, p-NPB, or any combination thereof:

[Electronic Apparatus]

The light-emitting device may be included in various electronic apparatuses.

In an embodiment, an electronic apparatus including the light-emitting device may be a light-emitting apparatus, an authentication apparatus, or the like.

The electronic apparatus (for example, a light-emitting apparatus) may further include, in addition to the light-emitting device, a color filter, a color conversion layer, or a color filter and a color conversion layer. The color filter and/or the color conversion layer may be located in at least one traveling direction of light emitted from the light-emitting device. In an embodiment, the light emitted from the light-emitting device may be blue light or white light. The light-emitting device may be the same as described herein. In an embodiment, the color conversion layer may include quantum dots. The quantum dot may be, for example, a quantum dot as described herein.

The electronic apparatus may include a first substrate. The first substrate may include subpixels, the color filter may include color filter areas respectively corresponding to the subpixels, and the color conversion layer may include color conversion areas respectively corresponding to the subpixels.

A pixel-defining layer may be located between the subpixels to define each subpixel.

The color filter may further include color filter areas and light-shielding patterns located between the color filter areas, and the color conversion layer may include color conversion areas and light-shielding patterns located between the color conversion areas.

The color filter areas (or the color conversion areas) may include a first area emitting first color light, a second area emitting second color light, and/or a third area emitting third color light, and the first color light, the second color light, and/or the third color light may have different maximum emission wavelengths from one another. In an embodiment, the first color light may be red light, the second color light may be green light, and the third color light may be blue light. In an embodiment, the color filter areas (or the color conversion areas) may include quantum dots. For example, the first area may include a red quantum dot, the second area may include a green quantum dot, and the third area may not include a quantum dot. The quantum dot may be the same as described in the specification. The first area, the second area, and/or the third area may each further include a scatterer.

In an embodiment, the light-emitting device may emit a first light, the first area may absorb the first light to emit a first-first color light, the second area may absorb the first light to emit a second-first color light, and the third area may absorb the first light to emit a third-first color light. The first-first color light, the second-first color light, and the third-first color light may each have different maximum emission wavelengths. For example, the first light may be blue light, the first-first color light may be red light, the second-first color light may be green light, and the third-first color light may be blue light.

The electronic apparatus may further include a thin-film transistor, in addition to the light-emitting device as described herein. The thin-film transistor may include a source electrode, a drain electrode, and an active layer, wherein any one of the source electrode and the drain electrode may be electrically connected to any one of the first electrode and the second electrode of the light-emitting device.

The thin-film transistor may further include a gate electrode, a gate insulating film, etc.

The active layer may include crystalline silicon, amorphous silicon, an organic semiconductor, an oxide semiconductor, or the like.

The electronic apparatus may further include a sealing portion for sealing the light-emitting device. The sealing portion may be located between the color filter and/or the color-conversion layer, and the light-emitting device. The sealing portion may allow light from the light-emitting device to be extracted to the outside, and may simultaneously prevent ambient air and moisture from penetrating into the light-emitting device. The sealing portion may be a sealing substrate including a transparent glass substrate or a plastic substrate. The sealing portion may be a thin-film encapsulation layer including an organic layer and/or an inorganic layer. When the sealing portion is a thin-film encapsulation layer, the electronic apparatus may be flexible.

Various functional layers may be further included on the sealing portion, in addition to the color filter and/or the color conversion layer, according to the use of the electronic apparatus. The functional layers may include a touch screen layer, a polarizing layer, an authentication apparatus, and the like. The touch screen layer may be a pressure-sensitive touch screen layer, a capacitive touch screen layer, or an infrared touch screen layer. The authentication apparatus may be, for example, a biometric authentication apparatus that authenticates an individual by utilizing biometric information of a living body (for example, fingertips, pupils, etc.).

The authentication apparatus may further include, in addition to the light-emitting device, a biometric information collector.

The electronic apparatus may be applied to various displays, light sources, lighting, personal computers (for example, a mobile personal computer), mobile phones, digital cameras, electronic diaries, electronic dictionaries, electronic game machines, medical instruments (for example, electronic thermometers, sphygmomanometers, blood glucose meters, pulse measurement devices, pulse wave measurement devices, electrocardiogram displays, ultrasonic diagnostic devices, or endoscope displays), fish finders, various measuring instruments, meters (for example, meters for a vehicle, an aircraft, and a vessel), projectors, and the like.

[Description of FIGS. 2 and 3 ]

FIG. 2 is a schematic cross-sectional view of an electronic apparatus according to an embodiment.

The electronic apparatus of FIG. 2 includes a substrate 100, a thin-film transistor (TFT), a light-emitting device, and an encapsulation portion 300 that seals the light-emitting device.

The substrate 100 may be a flexible substrate, a glass substrate, or a metal substrate. A buffer layer 210 may be formed on the substrate 100. The buffer layer 210 may prevent penetration of impurities through the substrate 100 and may provide a flat surface on the substrate 100.

A TFT may be located on the buffer layer 210. The TFT may include an active layer 220, a gate electrode 240, a source electrode 260, and a drain electrode 270.

The active layer 220 may include an inorganic semiconductor such as silicon or polysilicon, an organic semiconductor, or an oxide semiconductor, and may include a source region, a drain region, and a channel region.

A gate insulating film 230 for insulating the active layer 220 from the gate electrode 240 may be located on the active layer 220, and the gate electrode 240 may be located on the gate insulating film 230.

An interlayer insulating film 250 is located on the gate electrode 240. The interlayer insulating film 250 may be placed between the gate electrode 240 and the source electrode 260 to insulate the gate electrode 240 from the source electrode 260 and between the gate electrode 240 and the drain electrode 270 to insulate the gate electrode 240 from the drain electrode 270.

The source electrode 260 and the drain electrode 270 may be located on the interlayer insulating film 250. The interlayer insulating film 250 and the gate insulating film 230 may be formed to expose the source region and the drain region of the active layer 220, and the source electrode 260 and the drain electrode 270 may respectively contact the exposed portions of the source region and the drain region of the active layer 220.

The TFT is electrically connected to a light-emitting device to drive the light-emitting device, and is covered by a passivation layer 280. The passivation layer 280 may include an inorganic insulating film, an organic insulating film, or any combination thereof. A light-emitting device is provided on the passivation layer 280. The light-emitting device may include a first electrode 110, an interlayer 130, and a second electrode 150.

The first electrode 110 may be located on the passivation layer 280. The passivation layer 280 may not completely cover the drain electrode 270 and may expose a portion of the drain electrode 270, and the first electrode 110 may be electrically connected to the exposed portion of the drain electrode 270.

A pixel-defining layer 290 including an insulating material may be located on the first electrode 110. The pixel-defining layer 290 may expose a region of the first electrode 110, and an interlayer 130 may be formed in the exposed region of the first electrode 110. The pixel-defining layer 290 may be a polyimide or polyacrylic organic film. Although not shown in FIG. 2 , at least some layers of the interlayer 130 may extend beyond the upper portion of the pixel-defining layer 290 to be provided in the form of a common layer.

The second electrode 150 may be located on the interlayer 130, and a capping layer 170 may be further included on the second electrode 150. The capping layer 170 may be formed to cover the second electrode 150.

The encapsulation portion 300 may be located on the capping layer 170. The encapsulation portion 300 may be located on a light-emitting device to protect the light-emitting device from moisture and/or oxygen. The encapsulation portion 300 may include: an inorganic film including silicon nitride (SiNx), silicon oxide (SiOx), indium tin oxide, indium zinc oxide, or any combination thereof; an organic film including polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyimide, polyethylene sulfonate, polyoxymethylene, polyarylate, hexamethyldisiloxane, an acrylic resin (for example, polymethyl methacrylate, polyacrylic acid, or the like), an epoxy-based resin (for example, aliphatic glycidyl ether (AGE), or the like), or a combination thereof; or a combination of the inorganic film and the organic film.

FIG. 3 is a schematic cross-sectional view of an electronic apparatus according to another embodiment.

The electronic apparatus of FIG. 3 may differ from the electronic apparatus of FIG. 2 , at least in that a light-shielding pattern 500 and a functional region 400 are further included on the encapsulation portion 300. The functional region 400 may be a color filter area, a color conversion area, or a combination of the color filter area and the color conversion area. In an embodiment, the light-emitting device included in the electronic apparatus of FIG. 3 may be a tandem light-emitting device.

[Manufacture Method]

Respective layers included in the hole transport region, the emission layer, and respective layers included in the electron transport region may be formed in a certain region by using one or more suitable methods selected from vacuum deposition, spin coating, casting, Langmuir-Blodgett (LB) deposition, ink-jet printing, laser-printing, and laser-induced thermal imaging.

When layers constituting the hole transport region, an emission layer, and layers constituting the electron transport region are formed by vacuum deposition, the deposition may be performed at a deposition temperature of about 100° C. to about 500° C., a vacuum degree of about 10⁻⁸ torr to about 10⁻³ torr, and a deposition speed of about 0.01 Å/sec to about 100 Å/sec, depending on a material to be included in a layer to be formed and the structure of a layer to be formed.

Definitions of Terms

The term “C₃-C₆₀ carbocyclic group” as used herein may be a cyclic group consisting of carbon as the only ring-forming atoms and having 3 to 60 carbon atoms, and the term “C₁-C₆₀ heterocyclic group” as used herein may be a cyclic group that has 1 to 60 carbon atoms and further has, in addition to carbon, at least one heteroatom as a ring-forming atom. The C₃-C₆₀ carbocyclic group and the C₁-C₆₀ heterocyclic group may each be a monocyclic group consisting of one ring or a polycyclic group in which two or more rings are condensed with each other. In an embodiment, the C₁-C₆₀ heterocyclic group may have 3 to 61 ring-forming atoms.

The term “cyclic group” as used herein may include the C₃-C₆₀ carbocyclic group or the C₁-C₆₀ heterocyclic group.

The term “π electron-rich C₃-C₆₀ cyclic group” as used herein may be a cyclic group that has 3 to 60 carbon atoms and may not include *—N═*′ as a ring-forming moiety, and the term “π electron-deficient nitrogen-containing C₁-C₆₀ cyclic group” as used herein may be a heterocyclic group that has 1 to 60 carbon atoms and may include *—N═*′ as a ring-forming moiety.

In embodiments,

-   -   the C₃-C₆₀ carbocyclic group may be a T₁ group or a group in         which two or more T₁ groups are condensed with each other (for         example, a cyclopentadiene group, an adamantane group, a         norbornane group, a benzene group, a pentalene group, a         naphthalene group, an azulene group, an indacene group, an         acenaphthylene group, a phenalene group, a phenanthrene group,         an anthracene group, a fluoranthene group, a triphenylene group,         a pyrene group, a chrysene group, a perylene group, a pentaphene         group, a heptalene group, a naphthacene group, a picene group, a         hexacene group, a pentacene group, a rubicene group, a coronene         group, an ovalene group, an indene group, a fluorene group, a         spiro-bifluorene group, a benzofluorene group, an         indenophenanthrene group, or an indenoanthracene group),     -   the C₁-C₆₀ heterocyclic group may be a T2 group, a group in         which two or more T2 groups are condensed with each other, or a         group in which at least one T2 group and at least one T₁ group         are condensed with each other (for example, a pyrrole group, a         thiophene group, a furan group, an indole group, a benzoindole         group, a naphthoindole group, an isoindole group, a         benzoisoindole group, a naphthoisoindole group, a benzosilole         group, a benzothiophene group, a benzofuran group, a carbazole         group, a dibenzosilole group, a dibenzothiophene group, a         dibenzofuran group, an indenocarbazole group, an indolocarbazole         group, a benzofurocarbazole group, a benzothienocarbazole group,         a benzosilolocarbazole group, a benzoindolocarbazole group, a         benzocarbazole group, a benzonaphthofuran group, a         benzonaphthothiophene group, a benzonaphthosilole group, a         benzofurodibenzofuran group, a benzofurodibenzothiophene group,         a benzothienodibenzothiophene group, a pyrazole group, an         imidazole group, a triazole group, an oxazole group, an         isoxazole group, an oxadiazole group, a thiazole group, an         isothiazole group, a thiadiazole group, a benzopyrazole group, a         benzimidazole group, a benzoxazole group, a benzoisoxazole         group, a benzothiazole group, a benzoisothiazole group, a         pyridine group, a pyrimidine group, a pyrazine group, a         pyridazine group, a triazine group, a quinoline group, an         isoquinoline group, a benzoquinoline group, a benzoisoquinoline         group, a quinoxaline group, a benzoquinoxaline group, a         quinazoline group, a benzoquinazoline group, a phenanthroline         group, a cinnoline group, a phthalazine group, a naphthyridine         group, an imidazopyridine group, an imidazopyrimidine group, an         imidazotriazine group, an imidazopyrazine group, an         imidazopyridazine group, an azacarbazole group, an azafluorene         group, an azadibenzosilole group, an azadibenzothiophene group,         an azadibenzofuran group, etc.),     -   the π electron-rich C₃-C₆₀ cyclic group may be a T₁ group, a         group in which two or more T₁ groups are condensed with each         other, a T3 group, a group in which two or more T3 groups are         condensed with each other, or a group in which at least one T3         group and at least one T₁ group are condensed with each other         (for example, a C₃-C₆₀ carbocyclic group, a 1H-pyrrole group, a         silole group, a borole group, a 2H-pyrrole group, a 3H-pyrrole         group, a thiophene group, a furan group, an indole group, a         benzoindole group, a naphthoindole group, an isoindole group, a         benzoisoindole group, a naphthoisoindole group, a benzosilole         group, a benzothiophene group, a benzofuran group, a carbazole         group, a dibenzosilole group, a dibenzothiophene group, a         dibenzofuran group, an indenocarbazole group, an indolocarbazole         group, a benzofurocarbazole group, a benzothienocarbazole group,         a benzosilolocarbazole group, a benzoindolocarbazole group, a         benzocarbazole group, a benzonaphthofuran group, a         benzonaphthothiophene group, a benzonaphthosilole group, a         benzofurodibenzofuran group, a benzofurodibenzothiophene group,         a benzothienodibenzothiophene group, etc.), and     -   the π electron-deficient nitrogen-containing C₁-C₆₀ cyclic group         may be a T4 group, a group in which two or more T4 groups are         condensed with each other, a group in which at least one T4         group and at least one T₁ group are condensed with each other, a         group in which at least one T4 group and at least one T3 group         are condensed with each other, or a group in which at least one         T4 group, at least one T₁ group, and at least one T3 group are         condensed with one another (for example, a pyrazole group, an         imidazole group, a triazole group, an oxazole group, an         isoxazole group, an oxadiazole group, a thiazole group, an         isothiazole group, a thiadiazole group, a benzopyrazole group, a         benzimidazole group, a benzoxazole group, a benzoisoxazole         group, a benzothiazole group, a benzoisothiazole group, a         pyridine group, a pyrimidine group, a pyrazine group, a         pyridazine group, a triazine group, a quinoline group, an         isoquinoline group, a benzoquinoline group, a benzoisoquinoline         group, a quinoxaline group, a benzoquinoxaline group, a         quinazoline group, a benzoquinazoline group, a phenanthroline         group, a cinnoline group, a phthalazine group, a naphthyridine         group, an imidazopyridine group, an imidazopyrimidine group, an         imidazotriazine group, an imidazopyrazine group, an         imidazopyridazine group, an azacarbazole group, an azafluorene         group, an azadibenzosilole group, an azadibenzothiophene group,         an azadibenzofuran group, etc.),     -   wherein the T1 group may be a cyclopropane group, a cyclobutane         group, a cyclopentane group, a cyclohexane group, a cycloheptane         group, a cyclooctane group, a cyclobutene group, a cyclopentene         group, a cyclopentadiene group, a cyclohexene group, a         cyclohexadiene group, a cycloheptene group, an adamantane group,         a norbornane (or a bicyclo[2.2.1]heptane) group, a norbornene         group, a bicyclo[1.1.1]pentane group, a bicyclo[2.1.1]hexane         group, a bicyclo[2.2.2]octane group, or a benzene group,     -   the T2 group may be a furan group, a thiophene group, a         1H-pyrrole group, a silole group, a borole group, a 2H-pyrrole         group, a 3H-pyrrole group, an imidazole group, a pyrazole group,         a triazole group, a tetrazole group, an oxazole group, an         isoxazole group, an oxadiazole group, a thiazole group, an         isothiazole group, a thiadiazole group, an azasilole group, an         azaborole group, a pyridine group, a pyrimidine group, a         pyrazine group, a pyridazine group, a triazine group, a         tetrazine group, a pyrrolidine group, an imidazolidine group, a         dihydropyrrole group, a piperidine group, a tetrahydropyridine         group, a dihydropyridine group, a hexahydropyrimidine group, a         tetrahydropyrimidine group, a dihydropyrimidine group, a         piperazine group, a tetrahydropyrazine group, a dihydropyrazine         group, a tetrahydropyridazine group, or a dihydropyridazine         group,     -   the T3 group may be a furan group, a thiophene group, a         1H-pyrrole group, a silole group, or a borole group, and     -   the T4 group may be a 2H-pyrrole group, a 3H-pyrrole group, an         imidazole group, a pyrazole group, a triazole group, a tetrazole         group, an oxazole group, an isoxazole group, an oxadiazole         group, a thiazole group, an isothiazole group, a thiadiazole         group, an azasilole group, an azaborole group, a pyridine group,         a pyrimidine group, a pyrazine group, a pyridazine group, a         triazine group, or a tetrazine group.

The terms “cyclic group”, “C₃-C₆₀ carbocyclic group”, “C₁-C₆₀ heterocyclic group”, “π electron-rich C₃-C₆₀ cyclic group”, or “π electron-deficient nitrogen-containing C₁-C₆₀ cyclic group” as used herein may each be a group condensed to any cyclic group, a monovalent group, or a polyvalent group (for example, a divalent group, a trivalent group, a tetravalent group, etc.), depending on the structure of a formula for which the corresponding terms are used. For example, a “benzene group” may be a benzo group, a phenyl group, a phenylene group, or the like, which may be readily understand by those of ordinary skill in the art according to the structure of a formula including the “benzene group.”

In an embodiment, examples of a monovalent C₃-C₆₀ carbocyclic group and a monovalent C₁-C₆₀ heterocyclic group may include a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₁-C₆ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group. In an embodiment, examples of a divalent C₃-C₆₀ carbocyclic group and a divalent C₁-C₆₀ heterocyclic group may include a C₃-C₁₀ cycloalkylene group, a C₁-C₁₀ heterocycloalkylene group, a C₃-C₁₀ cycloalkenylene group, a C₁-C₁₀ heterocycloalkenylene group, a C₆-C₆₀ arylene group, a C₁-C₆₀ heteroarylene group, a divalent non-aromatic condensed polycyclic group, and a divalent non-aromatic condensed heteropolycyclic group.

The term “C₁-C₆₀ alkyl group” as used herein may be a linear or branched aliphatic hydrocarbon monovalent group that has 1 to 60 carbon atoms, and examples thereof may include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, a neopentyl group, an isopentyl group, a sec-pentyl group, a 3-pentyl group, a sec-isopentyl group, an n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, an n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, an n-decyl group, an isodecyl group, a sec-decyl group, and a tert-decyl group. The term “C₁-C₆₀ alkylene group” as used herein may be a divalent group having a same structure as the C₁-C₆₀ alkyl group.

The term “C₂-C₆₀ alkenyl group” as used herein may be a monovalent hydrocarbon group having at least one carbon-carbon double bond in the middle or at a terminus of a C₂-C₆₀ alkyl group, and examples thereof may include an ethenyl group, a propenyl group, and a butenyl group. The term “C₂-C₆₀ alkenylene group” as used herein may be a divalent group having a same structure as the C₂-C₆₀ alkenyl group.

The term “C₂-C₆₀ alkynyl group” as used herein may be a monovalent hydrocarbon group having at least one carbon-carbon triple bond in the middle or at a terminus of a C₂-C₆₀ alkyl group, and examples thereof may include an ethynyl group and a propynyl group. The term “C₂-C₆₀ alkynylene group” as used herein may be a divalent group having a same structure as the C₂-C₆₀ alkynyl group.

The term “C₁-C₆₀ alkoxy group” as used herein may be a monovalent group represented by —O(A₁₀₁) (wherein A₁₀₁ may be a C₁-C₆₀ alkyl group), and examples thereof may include a methoxy group, an ethoxy group, and an isopropyloxy group.

The term “C₃-C₁₀ cycloalkyl group” as used herein may be a monovalent saturated hydrocarbon cyclic group having 3 to 10 carbon atoms, and examples thereof may include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an adamantanyl group, a norbornanyl group (or a bicyclo[2.2.1]heptyl group), a bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, and a bicyclo[2.2.2]octyl group. The term “C₃-C₁₀ cycloalkylene group” as used herein may be a divalent group having a same structure as the C₃-C₁₀ cycloalkyl group.

The term “C₁-C₁₀ heterocycloalkyl group” as used herein may be a monovalent cyclic group that further includes, in addition to a carbon atom, at least one heteroatom as a ring-forming atom and has 1 to 10 carbon atoms, and examples thereof may include a 1,2,3,4-oxatriazolidinyl group, a tetrahydrofuranyl group, and a tetrahydrothiophenyl group. The term “C₁-C₁₀ heterocycloalkylene group” as used herein may be a divalent group having a same structure as the C₁-C₁₀ heterocycloalkyl group.

The term “C₃-C₁₀ cycloalkenyl group” as used herein may be a monovalent cyclic group that has three to ten carbon atoms and at least one carbon-carbon double bond in the ring thereof and no aromaticity, and examples thereof may include a cyclopentenyl group, a cyclohexenyl group, and a cycloheptenyl group. The term “C₃-C₁₀ cycloalkenylene group” as used herein may be a divalent group having a same structure as the C₃-C₁₀ cycloalkenyl group.

The term “C₁-C₁₀ heterocycloalkenyl group” as used herein may be a monovalent cyclic group that has, in addition to a carbon atom, at least one heteroatom as a ring-forming atom, 1 to 10 carbon atoms, and at least one carbon-carbon double bond in the cyclic structure thereof. Examples of a C₁-C₁₀ heterocycloalkenyl group may be include a 4,5-dihydro-1,2,3,4-oxatriazolyl group, a 2,3-dihydrofuranyl group, and a 2,3-dihydrothiophenyl group. The term “C₁-C₁₀ heterocycloalkenylene group” as used herein may be a divalent group having a same structure as the C₁-C₁₀ heterocycloalkenyl group.

The term “C₆-C₆₀ aryl group” as used herein may be a monovalent group having a carbocyclic aromatic system of six to sixty carbon atoms, and the term “C₆-C₆₀ arylene group” as used herein may be a divalent group having a carbocyclic aromatic system of 6 to 60 carbon atoms. Examples of a C₆-C₆₀ aryl group may include a phenyl group, a pentalenyl group, a naphthyl group, an azulenyl group, an indacenyl group, an acenaphthyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a perylenyl group, a pentaphenyl group, a heptalenyl group, a naphthacenyl group, a picenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, and an ovalenyl group. When the C₆-C₆₀ aryl group and the C₆-C₆₀ arylene group each independently include two or more rings, the respective rings may be condensed with each other.

The term “C₁-C₆₀ heteroaryl group” as used herein may be a monovalent group having a heterocyclic aromatic system that has, in addition to a carbon atom, at least one heteroatom as a ring-forming atom, and 1 to 60 carbon atoms. The term “C₁-C₆₀ heteroarylene group” as used herein may be a divalent group having a heterocyclic aromatic system that has, in addition to a carbon atom, at least one heteroatom as a ring-forming atom, and 1 to 60 carbon atoms. Examples of a C₁-C₆₀ heteroaryl group may include a pyridinyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, a triazinyl group, a quinolinyl group, a benzoquinolinyl group, an isoquinolinyl group, a benzoisoquinolinyl group, a quinoxalinyl group, a benzoquinoxalinyl group, a quinazolinyl group, a benzoquinazolinyl group, a cinnolinyl group, a phenanthrolinyl group, a phthalazinyl group, and a naphthyridinyl group. When the C₁-C₆₀ heteroaryl group and the C₁-C₆₀ heteroarylene group each independently include two or more rings, the respective rings may be condensed with each other.

The term “monovalent non-aromatic condensed polycyclic group” as used herein may be a monovalent group having two or more rings condensed to each other, only carbon atoms (for example, having 8 to 60 carbon atoms) as ring-forming atoms, and non-aromaticity in its molecular structure when considered as a whole. Examples of a monovalent non-aromatic condensed polycyclic group may include an indenyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, an indenophenanthrenyl group, and an indeno anthracenyl group. The term “divalent non-aromatic condensed polycyclic group” as used herein may be a divalent group having a same structure as a monovalent non-aromatic condensed polycyclic group.

The term “monovalent non-aromatic condensed heteropolycyclic group” as used herein may be a monovalent group having two or more rings condensed to each other, at least one heteroatom in addition to carbon atoms (for example, having 1 to 60 carbon atoms) as a ring-forming atom, and non-aromaticity in its molecular structure when considered as a whole. Examples of a monovalent non-aromatic condensed heteropolycyclic group may include a pyrrolyl group, a thiophenyl group, a furanyl group, an indolyl group, a benzoindolyl group, a naphtho indolyl group, an isoindolyl group, a benzoisoindolyl group, a naphthoisoindolyl group, a benzosilolyl group, a benzothiophenyl group, a benzofuranyl group, a carbazolyl group, a dibenzosilolyl group, a dibenzothiophenyl group, a dibenzofuranyl group, an azacarbazolyl group, an azafluorenyl group, an azadibenzosilolyl group, an azadibenzothiophenyl group, an azadibenzofuranyl group, a pyrazolyl group, an imidazolyl group, a triazolyl group, a tetrazolyl group, an oxazolyl group, an isoxazolyl group, a thiazolyl group, an isothiazolyl group, an oxadiazolyl group, a thiadiazolyl group, a benzopyrazolyl group, a benzimidazolyl group, a benzoxazolyl group, a benzothiazolyl group, a benzoxadiazolyl group, a benzothiadiazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, an imidazotriazinyl group, an imidazopyrazinyl group, an imidazopyridazinyl group, an indenocarbazolyl group, an indolocarbazolyl group, a benzofurocarbazolyl group, a benzothienocarbazolyl group, a benzosilolocarbazolyl group, a benzoindolocarbazolyl group, a benzocarbazolyl group, a benzonaphthofuranyl group, a benzonaphthothiophenyl group, a benzonaphthosilolyl group, a benzofurodibenzofuranyl group, a benzofurodibenzothiophenyl group, and a benzothienodibenzothiophenyl group. The term “divalent non-aromatic condensed heteropolycyclic group” as used herein may be a divalent group having a same structure as a monovalent non-aromatic condensed heteropolycyclic group.

The term “C₆-C₆₀ aryloxy group” as used herein may be a group represented by —O(A₁₀₂) (wherein A₁₀₂ may be a C₆-C₆₀ aryl group), and the term “C₆-C₆₀ arylthio group” as used herein may be a group represented by —S(A₁₀₃) (wherein A₁₀₃ may be a C₆-C₆₀ aryl group).

The term “C₇-C₆₀ aryl alkyl group” as used herein may be a group represented by -(A₁₀₄)(A₁₀₅) (wherein A₁₀₄ may be a C₁-C₅₄ alkylene group, and A₁₀₅ may be a C₆-C₅₉ aryl group), and the term “C₂-C₆₀ heteroaryl alkyl group” as used herein may be a group represented by -(A₁₀₆)(A₁₀₇) (wherein A₁₀₆ may be a C₁-C₅₉ alkylene group, and A₁₀₇ may be a C₁-C₅₉ heteroaryl group).

In the specification, the group “R_(a)” may be:

-   -   deuterium (-D), —F, —Cl, —Br, —I, a hydroxyl group, a cyano         group, or a nitro group;     -   a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl         group, or a C₁-C₆₀ alkoxy group, each unsubstituted or         substituted with deuterium, —F, —Cl, —Br, —I, a hydroxyl group,         a cyano group, a nitro group, a C₃-C₆₀ carbocyclic group, a         C₁-C₆₀ heterocyclic group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀         arylthio group, a C₇-C₆₀ aryl alkyl group, a C₂-C₆₀ heteroaryl         alkyl group, —Si(Q₁₁)(Q₁₂)(Q₁₃), —N(Q₁₁)(Q₁₂), —B(Q₁₁)(Q₁₂),         —C(═O)(Q₁₁), —S(═O)₂(Q₁₁), —P(═O)(Q₁₁)(Q₁₂), or any combination         thereof;     -   a C₃-C₆₀ carbocyclic group, a C₁-C₆₀ heterocyclic group, a         C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ aryl         alkyl group, or a C₂-C₆₀ heteroaryl alkyl group, each         unsubstituted or substituted with deuterium, —F, —Cl, —Br, —I, a         hydroxyl group, a cyano group, a nitro group, a C₁-C₆₀ alkyl         group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀         alkoxy group, a C₃-C₆₀ carbocyclic group, a C₁-C₆₀ heterocyclic         group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀         aryl alkyl group, a C₂-C₆₀ heteroaryl alkyl group,         —Si(Q₂₁)(Q₂₂)(Q₂₃), —N(Q₂₁)(Q₂₂), —B(Q₂₁)(Q₂₂), —C(═O)(Q₂₁),         —S(═O)₂(Q₂₁), —P(═O)(Q₂₁)(Q₂₂), or any combination thereof; or     -   —Si(Q₃₁)(Q₃₂)(Q₃₃), —N(Q₃₁)(Q₃₂), —B(Q₃₁)(Q₃₂), —C(═O)(Q₃₁),         —S(═O)₂(Q₃₁), or —P(═O)(Q₃₁)(Q₃₂).

In the specification, Q₁ to Q₃, Q₁₁ to Q₁₃, Q₂₁ to Q₂₃, and Q₃₁ to Q₃₃ may each independently be: hydrogen; deuterium; —F; —Cl; —Br; —I; a hydroxyl group; a cyano group; a nitro group; a C₁-C₆₀ alkyl group; a C₂-C₆₀ alkenyl group; a C₂-C₆₀ alkynyl group; a C₁-C₆₀ alkoxy group; or a C₃-C₆₀ carbocyclic group, a C₁-C₆₀ heterocyclic group, a C₇-C₆₀ aryl alkyl group, or a C₂-C₆₀ heteroaryl alkyl group, each unsubstituted or substituted with deuterium, —F, a cyano group, a C₁-C₆₀ alkyl group, a C₁-C₆₀ alkoxy group, a phenyl group, a biphenyl group, or any combination thereof.

The term “heteroatom” as used herein may be any atom other than a carbon atom or a hydrogen atom. Examples of a heteroatom may include O, S, N, P, Si, B, Ge, Se, or any combination thereof.

The term “Ph” as used herein refers to a phenyl group, the term “Me” as used herein refers to a methyl group, the term “Et” as used herein refers to an ethyl group, the terms “tert-Bu” or “Bu^(t)” as used herein each refer to a tert-butyl group, and the term “OMe” as used herein refers to a methoxy group.

The term “biphenyl group” as used herein may be a “phenyl group substituted with a phenyl group.” For example, the “biphenyl group” may be a substituted phenyl group having a C₆-C₆₀ aryl group as a substituent.

The term “terphenyl group” as used herein may be a “phenyl group substituted with a biphenyl group”. For example, the “terphenyl group” may be a substituted phenyl group having, as a substituent, a C₆-C₆₀ aryl group substituted with a C₆-C₆₀ aryl group.

The symbols * and *′ as used herein, unless defined otherwise, each refer to a binding site to a neighboring atom in a corresponding formula or moiety.

The term “sensitizer” as used herein may be a compound that helps to increase quantum efficiency by transferring excitons to a light-emitting dopant.

Hereinafter, a light-emitting device according to embodiments will be described in detail with reference to the Examples.

EXAMPLES Example 1

An ITO glass substrate was cut to a size of 50 mm×50 mm×0.5 mm, sonicated by utilizing isopropyl alcohol and pure water, each for 15 minutes, and cleaned by exposure to ultraviolet rays-ozone for 30 minutes.

HT3 was vacuum-deposited on the ITO substrate to form a hole injection layer having a thickness of 1,200 Å, and Compound HT47 was vacuum-deposited thereon to form a hole transport layer having a thickness of 50 Å.

Compounds HT47, ET18, 3-1, and 4-16 (at a weight ratio of 7:3:1:0.1) were co-deposited thereon to form an emission layer having a thickness of 300 Å.

ET46 and Liq (at a weight ratio of 5:5) were co-deposited thereon to form an electron transport layer having a thickness of 200 Å, Liq was deposited thereon to form an electron injection layer having a thickness of 10 Å, and Mg:Ag were co-deposited thereon to form a cathode having a thickness of 100 Å, thereby completing of manufacture of an organic electroluminescent device.

Example 2

An organic light-emitting device was manufactured in the same manner as in Example 1, except that, in forming the emission layer, a weight ratio of Compound 3-1 to Compound 4-16 was changed to 1:0.3.

Example 3

An organic light-emitting device was manufactured in the same manner as in Example 1, except that, in forming the emission layer, a weight ratio of Compound 3-1 to Compound 4-16 was changed to 1:0.5.

Example 4

An organic light-emitting device was manufactured in the same manner as in Example 1, except that, in forming the emission layer, a weight ratio of Compound 3-1 to Compound 4-16 was changed to 1:1.

Example 5

An organic light-emitting device was manufactured in the same manner as in Example 1, except that, in forming the emission layer, Compound 3-2 was utilized instead of Compound 3-1, Compound 4-28 was utilized instead of Compound 4-16, and a weight ratio of Compound 3-2 to Compound 4-28 was changed to 1:0.5.

Example 6

An organic light-emitting device was manufactured in the same manner as in Example 1, except that, in forming the emission layer, Compound 7-4 was added to Compound 3-1 and Compound 4-16, and a weight ratio of Compound 3-1: Compound 4-16: Compound 7-4 was changed to 1:0.3:0.3.

Comparative Example 1

An organic light-emitting device was manufactured in the same manner as in Example 1, except that, in forming the emission layer, a weight ratio of Compound 3-1 to Compound 4-16 was changed to 1:0.

Comparative Example 2

An organic light-emitting device was manufactured in the same manner as in Example 1, except that, in forming the emission layer, a weight ratio of Compound 3-1 to Compound 4-16 was changed to 0:1.

Comparative Example 3

An organic light-emitting device was manufactured in the same manner as in Example 3, except that, in forming the emission layer, Compound 4-C was utilized instead of Compound 4-16.

Evaluation Example

The driving voltage (V) at 1,000 nits of the luminance, current efficiency (Cd/A), and lifespan (T95) of the organic light-emitting devices manufactured in Examples 1 to 6 and Comparative Examples 1 to 3 were measured, and are shown in Table 1 as relative values (%) with respect to the measured values of Comparative Example 1. The driving voltage and efficiency of the organic light-emitting devices were measured by utilizing a current voltmeter Keithley SMU 236 and a luminance meter PR650, and the lifespan is a measure of the time that lapsed when the luminance was 95% of initial luminance.

TABLE 1 Driving voltage Current Emission layer comparison efficiency LT95 Color coordinate (weight ratio) (%) (%) (%) CIEx CIEy Example 1 Compound 3-1:Compound 4-16 100%  103% 101% 0.135 0.058 (1:0.1) Example 2 Compound 3-1:Compound 4-16 99% 108% 112% 0.137 0.052 (1:0.3) Example 3 Compound 3-1:Compound 4-16 97% 107% 101% 0.136 0.056 (1:0.5) Example 4 Compound 3-1:Compound 4-16 95% 102%  95% 0.137 0.056 (1:1) Example 5 Compound 3-2:Compound 4-28 97% 109% 109% 0.136 0.055 (1:0.5) Example 6 Compound 3-1:Compound 4-16:Compound7-4 98% 120% 110% 0.138 0.053. (1:0.3:0.3) Comparative Compound 3-1 100%  100% 100% 0.134 0.057 Example 1 Comparative Compound 4-16 87% 121%  20% 0.137 0.052 Example 2 Comparative Compound 3-1:Compound 4-C 97% 101%  63% 0.134 0.057 Example 3 (1:0.5)

Referring to Table 1, it could be confirmed that the organic light-emitting devices of Examples 1 to 6 had improved driving voltage, color purity, efficiency, and/or lifespan, as compared to the organic light-emitting devices of Comparative Examples 1 to 3.

The organic light-emitting device has low driving voltage, high efficiency, and long lifespan.

Embodiments have been disclosed herein, and although terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. In some instances, as would be apparent by one of ordinary skill in the art, features, characteristics, and/or elements described in connection with an embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the disclosure as set forth in the claims. 

What is claimed is:
 1. An organic light-emitting device comprising: a first electrode; a second electrode facing the first electrode; and an interlayer between the first electrode and the second electrode and comprising an emission layer, wherein the emission layer comprises a first compound, a second compound, a third compound, and a fourth compound, the first compound is a hole transporting host, the second compound is an electron transporting host, the third compound is a platinum (Pt) complex, and the fourth compound is an iridium (Ir) complex including a halogen group.
 2. The organic light-emitting device of claim 1, wherein the third compound is represented by Formula 3:

wherein in Formula 3, CY₁ to CY₄ are each independently a C₅-C₃₀ carbocyclic group or a C₁-C₃₀ heterocyclic group, L₁ to L₃ are each independently a single bond, a double bond, a substituted or unsubstituted C₆-C₃₀ arylene group, a substituted or unsubstituted C₁-C₃₀ heteroarylene group, *—O—*′, *—S—*′, *—C(═O)—*′, *—S(═O)—*′, *—C(Q₁)(Q₂)-*′, *—C(Q₁)=C(Q₂)-*′, *—C(Q₁)=*′, *—Si(Q₁)(Q₂)-*′, *—B(Q₁)-*′, *—N(Q₁)-*′, or *—P(Q₁)-*′, T₁ to T₄ are each independently a chemical bond, *—O—*′, *—S—*′, *—B(Q₃)-*′, *—N(Q₃)-*′, *—P(Q₃)-*′, *—C(Q₃)(Q₄)-*, *—Si(Q₃)(Q₄)-*′, *—Ge(Q₃)(Q₄)-*′, *—C(═O)—*′, or *—C(═S)—*′, R₁ to R₄ are each independently deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —C(Q₅)(Q₆)(Q₇), —Si(Q₅)(Q₆)(Q₇), —B(Q₅)(Q₆), —N(Q₅)(Q₆), —P(Q₅)(Q₆), —C(═O)(Q₅), —S(═O)(Q₅), —S(═O)₂(Q₅), —P(═O)(Q₅)(Q₆), or —P(═S)(Q₅)(Q₆), neighboring groups among R₁ to R₄ and L₁ to L₃ are optionally bonded to each other to form a substituted or unsubstituted C₅-C₆₀ carbocyclic group or a substituted or unsubstituted C₁-C₆₀ heterocyclic group, a1 to a3 are each independently an integer from 0 to 3, b1 to b4 are each independently an integer from 0 to 10, at least one of substituents of the substituted C₆-C₃₀ arylene group, the substituted C₁-C₃₀ heteroarylene group, the substituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀ alkenyl group, the substituted C₂-C₆₀ alkynyl group, the substituted C₁-C₆₀ alkoxy group, the substituted C₃-C₁₀ cycloalkyl group, the substituted C₁-C₁₀ heterocycloalkyl group, the substituted C₃-C₁₀ cycloalkenyl group, the substituted C₁-C₁₀ heterocycloalkenyl group, the substituted C₆-C₆₀ aryl group, the substituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀ arylthio group, the substituted C₁-C₆₀ heteroaryl group, the substituted monovalent non-aromatic condensed polycyclic group, the substituted monovalent non-aromatic condensed heteropolycyclic group, the substituted C₅-C₆₀ carbocyclic group, and the substituted C₁-C₆₀ heterocyclic group is: deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, or a C₁-C₆₀ alkoxy group; a C₁-C₆ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, or a C₁-C₆₀ alkoxy group, each substituted with deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —Si(Q₁₁)(Q₁₂)(Q₁₃), —N(Q₁₁)(Q₁₂), —B(Q₁₁)(Q₁₂), —C(═O)(Q₁₁), —S(═O)₂(Q₁₁), —P(═O)(Q₁₁)(Q₁₂), or a combination thereof; a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, or a monovalent non-aromatic condensed heteropolycyclic group; a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, or a monovalent non-aromatic condensed heteropolycyclic group, each substituted with deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —Si(Q₂₁)(Q₂₂)(Q₂₃), —N(Q₂₁)(Q₂₂), —B(Q₂₁)(Q₂₂), —C(═O)(Q₂₁), —S(═O)₂(Q₂₁), —P(═O)(Q₂₁)(Q₂₂), or a combination thereof; or —Si(Q₃₁)(Q₃₂)(Q₃₃), —N(Q₃₁)(Q₃₂), —B(Q₃₁)(Q₃₂), —C(═O)(Q₃₁), —S(═O)₂(Q₃₁), or —P(═O)(Q₃₁)(Q₃₂), and Q₁ to Q₇, Q₁₁ to Q₁₃, Q₂₁ to Q₂₃, and Q₃₁ to Q₃₃ are each independently hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, or a terphenyl group.
 3. The organic light-emitting device of claim 2, wherein the third compound is represented by Formula 3A:

wherein in Formula 3A, CY₁₃ and CY₁₄ are each independently a benzene group, a naphthalene group, an anthracene group, a phenanthrene group, a triphenylene group, a pyrene group, a chrysene group, a cyclopentadiene group, a 1,2,3,4-tetrahydronaphthalene group, a carbene group, a thiophene group, a furan group, a selenophene group, an indole group, a benzoborole group, a benzophosphole group, an indene group, a benzosilole group, a benzogermole group, a benzothiophene group, a benzoselenophene group, a benzofuran group, a carbazole group, a dibenzoborole group, a dibenzophosphole group, a fluorene group, a dibenzosilole group, a dibenzogermole group, a dibenzothiophene group, a dibenzoselenophene group, a dibenzofuran group, a dibenzothiophene 5-oxide group, a 9H-fluorene-9-one group, a dibenzothiophene 5,5-dioxide group, an azaindole group, an azabenzoborole group, an azabenzophosphole group, an azaindene group, an azabenzosilole group, an azabenzogermole group, an azabenzothiophene group, an azabenzoselenophene group, an azabenzofuran group, an azacarbazole group, an azadibenzoborole group, an azadibenzophosphole group, an azafluorene group, an azadibenzosilole group, an azadibenzogermole group, an azadibenzothiophene group, an azadibenzoselenophene group, an azadibenzofuran group, an azadibenzothiophene 5-oxide group, an aza-9H-fluorene-9-one group, an azadibenzothiophene 5,5-dioxide group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrrole group, a pyrazole group, an imidazole group, a triazole group, an oxazole group, an isooxazole group, a thiazole group, an isothiazole group, an oxadiazole group, a thiadiazole group, a benzopyrazole group, a benzimidazole group, a benzoxazole group, a benzothiazole group, a benzoxadiazole group, a benzothiadiazole group, a 5,6,7,8-tetrahydroisoquinoline group, or a 5,6,7,8-tetrahydroquinoline group, X₁₃ and X₁₄ are each independently N or C, L₁₂ and L₁₃ are each independently a single bond, a double bond, *—O—*′, *—S—*′, *—C(═O)—*′, *—S(═O)—*′, *—C(Q₁)(Q₂)-*′, *—C(Q₁)=C(Q₂)-*′, *—C(Q₁)=*′, *—Si(Q₁)(Q₂)-*′, *—B(Q₁)-*′, *—N(Q₁)-*′, or *—P(Q₁)-*′, T₁₁ to T₁₄ are each independently a chemical bond, *—O—*′, or *—S—*′, a12 and a13 are each independently an integer from 0 to 3, b13 and b14 are each independently an integer from 0 to 10, R_(11a), R_(11b), R_(11c), R_(12a), R_(12b), R_(12c), R₁₃, and R₁₄ are each independently: hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, a C₁-C₂₀ alkyl group, or a C₁-C₂₀ alkoxy group; a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted with deuterium, —F, —Cl, —Br, —I, a cyano group, a phenyl group, a biphenyl group, or a combination thereof; a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a spiro-fluorene-benzofluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a pyrenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, a silolyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an indolyl group, an isoindolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, a benzosilolyl group, a benzoisothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a dibenzosilolyl group, a carbazolyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a thiadiazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, an oxazolopyridinyl group, a thiazolopyridinyl group, a benzonaphthyridinyl group, an azafluorenyl group, an azaspiro-bifluorenyl group, an azacarbazolyl group, an azadibenzofuranyl group, an azadibenzothiophenyl group, an azadibenzosilolyl group, —Si(Q₅)(Q₆)(Q₇), —N(Q₅)(Q₆), or —B(Q₅)(Q₆); or a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a spiro-fluorene-benzofluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a pyrenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, a silolyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an indolyl group, an isoindolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, a benzosilolyl group, a benzoisothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a dibenzosilolyl group, a carbazolyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a thiadiazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, an oxazolopyridinyl group, a thiazolopyridinyl group, a benzonaphthyridinyl group, an azafluorenyl group, an azaspiro-bifluorenyl group, an azacarbazolyl group, an azadibenzofuranyl group, an azadibenzothiophenyl group, or an azadibenzosilolyl group, each substituted with deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a spiro-fluorene-benzofluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a pyrenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, a silolyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an indolyl group, an isoindolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, a benzosilolyl group, a benzoisothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a dibenzosilolyl group, a carbazolyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a thiadiazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, an oxazolopyridinyl group, a thiazolopyridinyl group, a benzonaphthyridinyl group, an azafluorenyl group, an azaspiro-bifluorenyl group, an azacarbazolyl group, an azadibenzofuranyl group, an azadibenzothiophenyl group, an azadibenzosilolyl group, a biphenyl group, a terphenyl group, or a combination thereof, Q₁, Q₂, and Q₅ to Q₇ are each independently hydrogen, deuterium, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a triphenylenyl group, a biphenyl group, a terphenyl group, or a tetraphenyl group, and neighboring groups among R_(11a), R_(11b), R_(11c), R_(12a), R_(12b), R_(12c), R₁₃, R₁₄, L₁₂, and L₁₃ are optionally bonded to each other to form a substituted or unsubstituted C₅-C₆₀ carbocyclic group or a substituted or unsubstituted C₁-C₆₀ heterocyclic group.
 4. The organic light-emitting device of claim 1, wherein the third compound comprises one of Compounds 3-1 to 3-6:


5. The organic light-emitting device of claim 1, wherein the halogen group of the fourth compound is directly bonded to an Ir atom.
 6. The organic light-emitting device of claim 1, wherein the fourth compound is represented by Formula 4:

wherein in Formula 4, CY₅ and CY₆ are each independently a C₅-C₃₀ carbocyclic group or a C₁-C₃₀ heterocyclic group, each L₅ is independently a single bond, a double bond, a substituted or unsubstituted C₆-C₃₀ arylene group, a substituted or unsubstituted C₁-C₃₀ heteroarylene group, *—O—*′, *—S—*′, *—C(═O)—*′, *—S(═O)—*′, *—C(Q₁)(Q₂)-*′, *—C(Q₁)=C(Q₂)-*′, *—C(Q₁)=*′, *—Si(Q₁)(Q₂)-*′, *—B(Q₁)-*′, *—N(Q₁)-*′, or *—P(Q₁)-*′, T₇ is a chemical bond, *—O—*′, *—S—*′, *—B(Q₃)-*′, *—N(Q₃)-*′, *—P(Q₃)-*′, *—C(Q₃)(Q₄)-*, *—Si(Q₃)(Q₄)-*′, *—Ge(Q₃)(Q₄)-*′, *—C(═O)—*′, or *—C(═S)—*′, R₅ and R₆ are each independently deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —C(Q₅)(Q₆)(Q₇), —Si(Q₅)(Q₆)(Q₇), —B(Q₅)(Q₆), —N(Q₅)(Q₆), —P(Q₅)(Q₆), —C(═O)(Q₅), —S(═O)(Q₅), —S(═O)₂(Q₅), —P(═O)(Q₅)(Q₆), or —P(═S)(Q₅)(Q₆), Y₇ is a substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —C(Q₈)(Q₉)(Q₁₀), —Si(Q₈)(Q₉)(Q₁₀), —B(Q₈)(Q₉), —N(Q₈)(Q₉), —P(Q₈)(Q₉), —C(═O)(Q₈), —S(═O)(Q₈), —S(═O)₂(Q₈), —P(═O)(Q₈)(Q₉), or —P(═S)(Q₈)(Q₉), Q₁ to Q₁₀ are each independently hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, or a terphenyl group, a5 is an integer from 0 to 3, b5 and b6 are each independently an integer from 0 to 10, c7 is 0, 1, 2, or 3, d7 is 1, 2, or 3, and X is F, Cl, or I.
 7. The organic light-emitting device of claim 6, wherein in Formula 4, CY₅ and CY₆ are each independently a benzene group, a naphthalene group, an anthracene group, a phenanthrene group, a triphenylene group, a pyrene group, a chrysene group, a cyclopentadiene group, a 1,2,3,4-tetrahydronaphthalene group, a carbene group, a thiophene group, a furan group, a selenophene group, an indole group, a benzoborole group, a benzophosphole group, an indene group, a benzosilole group, a benzogermole group, a benzothiophene group, a benzoselenophene group, a benzofuran group, a carbazole group, a dibenzoborole group, a dibenzophosphole group, a fluorene group, a dibenzosilole group, a dibenzogermole group, a dibenzothiophene group, a dibenzoselenophene group, a dibenzofuran group, a dibenzothiophene 5-oxide group, a 9H-fluorene-9-one group, a dibenzothiophene 5,5-dioxide group, an azaindole group, an azabenzoborole group, an azabenzophosphole group, an azaindene group, an azabenzosilole group, an azabenzogermole group, an azabenzothiophene group, an azabenzoselenophene group, an azabenzofuran group, an azacarbazole group, an azadibenzoborole group, an azadibenzophosphole group, an azafluorene group, an azadibenzosilole group, an azadibenzogermole group, an azadibenzothiophene group, an azadibenzoselenophene group, an azadibenzofuran group, an azadibenzothiophene 5-oxide group, an aza-9H-fluorene-9-one group, an azadibenzothiophene 5,5-dioxide group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrrole group, a pyrazole group, an imidazole group, a triazole group, an oxazole group, an isooxazole group, a thiazole group, an isothiazole group, an oxadiazole group, a thiadiazole group, a benzopyrazole group, a benzimidazole group, a benzoxazole group, a benzothiazole group, a benzoxadiazole group, a benzothiadiazole group, a 5,6,7,8-tetrahydroisoquinoline group, or a 5,6,7,8-tetrahydroquinoline group, T₇ is a chemical bond, *—O—*′, or *—S—*′, L₅ is a single bond, and Y₇ is a substituted or unsubstituted C₂-C₂₀ alkenyl group, a substituted or unsubstituted C₆-C₂₀ aryl group, a substituted or unsubstituted C₂-C₂₀ heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, or a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group.
 8. The organic light-emitting device of claim 1, wherein the fourth compound comprises one of Compounds 4-1 to 4-30:


9. The organic light-emitting device of claim 1, further comprising a fifth compound, wherein the fifth compound is a fluorescent dopant or a delayed fluorescence dopant.
 10. The organic light-emitting device of claim 9, wherein the fifth compound comprises a compound represented by Formula 5, a compound represented by Formula 6, a compound represented by Formula 7, or a combination thereof:

wherein in Formula 5, Ar₅₃ is a substituted or unsubstituted C₅-C₆₀ carbocyclic group or a substituted or unsubstituted C₁-C₆₀ heterocyclic group, L₅₁ to L₅₃ are each independently a substituted or unsubstituted C₃-C₁₀ cycloalkylene group, a substituted or unsubstituted C₁-C₁₀heterocycloalkylene group, a substituted or unsubstituted C₃-C₁₀ cycloalkenylene group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkenylene group, a substituted or unsubstituted C₆-C₆₀ arylene group, a substituted or unsubstituted C₁-C₆₀ heteroarylene group, a substituted or unsubstituted divalent non-aromatic condensed polycyclic group, or a substituted or unsubstituted divalent non-aromatic condensed heteropolycyclic group, a51 to a53 are each independently an integer from 0 to 3, R₅₁ and R₅₂ are each independently a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, or a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, and n5 is an integer from 1 to 6, wherein in Formula 6, A₆₁ to A₆₃ are each independently a C₃-C₆₀ carbocyclic group or a C₁-C₆₀ heterocyclic group, X₆₁ is C(R₆₄)(R₆₅), N(R₆₄), O, or S, X₆₂ is C(R₆₆)(R₆₇), N(R₆₆), O, or S, L₆₁ to L₆₃ are each independently a C₃-C₆₀ carbocyclic group that is unsubstituted or substituted with at least one R_(a) or a C₁-C₆₀ heterocyclic group that is unsubstituted or substituted with at least one R_(a), a61 to a63 are each independently an integer from 0 to 5, R₆₁ to R₆₇ are each independently hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, a C₁-C₆₀ alkyl group that is unsubstituted or substituted with at least one R_(a), a C₂-C₆₀ alkenyl group that is unsubstituted or substituted with at least one R_(a), a C₂-C₆₀ alkynyl group that is unsubstituted or substituted with at least one R_(a), a C₁-C₆₀ alkoxy group that is unsubstituted or substituted with at least one R_(a), a C₃-C₆₀ carbocyclic group that is unsubstituted or substituted with at least one R_(a), a C₁-C₆₀ heterocyclic group that is unsubstituted or substituted with at least one R_(a), a C₆-C₆₀ aryloxy group that is unsubstituted or substituted with at least one R_(a), a C₆-C₆₀ arylthio group that is unsubstituted or substituted with at least one R_(a), —Si(Q₁)(Q₂)(Q₃), —N(Q₁)(Q₂), —B(Q₁)(Q₂), —C(═O)(Q₁), —S(═O)₂(Q₁), or —P(═O)(Q₁)(Q₂), and b61 to b63 and n61 to n63 are each independently an integer from 1 to 5, wherein in Formula 7, R₇₁ to R₇₅ are each independently hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, a C₁-C₆₀ alkyl group that is unsubstituted or substituted with at least one R_(a), a C₂-C₆₀ alkenyl group that is unsubstituted or substituted with at least one R_(a), a C₂-C₆₀ alkynyl group that is unsubstituted or substituted with at least one R_(a), a C₁-C₆₀ alkoxy group that is unsubstituted or substituted with at least one R_(a), a C₃-C₆₀ carbocyclic group that is unsubstituted or substituted with at least one R_(a), a C₁-C₆₀ heterocyclic group that is unsubstituted or substituted with at least one R_(a), a C₆-C₆₀ aryloxy group that is unsubstituted or substituted with at least one R_(a), a C₆-C₆₀ arylthio group that is unsubstituted or substituted with at least one R_(a), —Si(Q₁)(Q₂)(Q₃), —N(Q₁)(Q₂), —B(Q₁)(Q₂), —C(═O)(Q₁), —S(═O)₂(Q₁), or —P(═O)(Q₁)(Q₂), b73 and b74 are each independently an integer from 0 to 4, and b75 may be an integer from 0 to 6, R_(a) is: deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, or a nitro group; a C₁-C₆ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, or a C₁-C₆₀ alkoxy group, each unsubstituted or substituted with deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, a C₃-C₆₀ carbocyclic group, a C₁-C₆₀ heterocyclic group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ aryl alkyl group, a C₂-C₆₀ heteroaryl alkyl group, —Si(Q₁₁)(Q₁₂)(Q₁₃), —N(Q₁₁)(Q₁₂), —B(Q₁₁)(Q₁₂), —C(═O)(Q₁₁), —S(═O)₂(Q₁₁), —P(═O)(Q₁₁)(Q₁₂), or a combination thereof; a C₃-C₆₀ carbocyclic group, a C₁-C₆₀ heterocyclic group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ aryl alkyl group, or a C₂-C₆₀ heteroaryl alkyl group, each unsubstituted or substituted with deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₆₀ carbocyclic group, a C₁-C₆₀ heterocyclic group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ aryl alkyl group, a C₂-C₆₀ heteroaryl alkyl group, —Si(Q₂₁)(Q₂₂)(Q₂₃), —N(Q₂₁)(Q₂₂), —B(Q₂₁)(Q₂₂), —C(═O)(Q₂₁), —S(═O)₂(Q₂₁), —P(═O)(Q₂₁)(Q₂₂), or a combination thereof; or —Si(Q₃₁)(Q₃₂)(Q₃₃), —N(Q₃₁)(Q₃₂), —B(Q₃₁)(Q₃₂), —C(═O)(Q₃₁), —S(═O)₂(Q₃₁), or —P(═O)(Q₃₁)(Q₃₂), and Q₁ to Q₃, Q₁₁ to Q₁₃, Q₂₁ to Q₂₃, and Q₃₁ to Q₃₃ are each independently: hydrogen; deuterium; —F; —Cl; —Br; —I; a hydroxyl group; a cyano group; a nitro group; a C₁-C₆₀ alkyl group; a C₂-C₆₀ alkenyl group; a C₂-C₆₀ alkynyl group; a C₁-C₆₀ alkoxy group; or a C₃-C₆₀ carbocyclic group, a C₁-C₆₀ heterocyclic group, a C₇-C₆₀ aryl alkyl group, or a C₂-C₆₀ heteroaryl alkyl group, each unsubstituted or substituted with deuterium, —F, a cyano group, a C₁-C₆₀ alkyl group, a C₁-C₆₀ alkoxy group, a phenyl group, a biphenyl group, or a combination thereof.
 11. The organic light-emitting device of claim 10, wherein the compound represented by Formula 5 comprises at least one of Compounds 5-1 to 5-4, the compound represented by Formula 6 comprises at least one of Compounds 6-1 to 6-6, and the compound represented by Formula 7 comprises at least one of Compounds 7-1 and 7-2:


12. The organic light-emitting device of claim 1, wherein an emission peak wavelength of an emission spectrum of the third compound is greater than an emission peak wavelength of an emission spectrum of the fourth compound.
 13. The organic light-emitting device of claim 1, wherein an emission peak wavelength of the emission layer is in a range of about 430 nm to about 480 nm.
 14. The organic light-emitting device of claim 1, wherein a ratio of emission components emitted from the third compound to total emission components emitted from the emission layer is greater than or equal to about 80%.
 15. The organic light-emitting device of claim 9, wherein an emission peak wavelength of an emission spectrum of the fifth compound is greater than an emission peak wavelength of an emission spectrum of the fourth compound.
 16. The organic light-emitting device of claim 9, wherein an emission peak wavelength of the emission layer is in a range of about 430 nm to about 480 nm.
 17. The organic light-emitting device of claim 9, wherein a ratio of emission components emitted from the fifth compound to total emission components emitted from the emission layer is greater than or equal to about 80%.
 18. An electronic apparatus comprising the organic light-emitting device of claim
 1. 19. The electronic apparatus of claim 18, further comprising a thin-film transistor, wherein the thin-film transistor comprises a source electrode, a drain electrode, an active layer, and a gate electrode, and the first electrode of the organic light-emitting device is electrically connected to the source electrode or the drain electrode.
 20. The electronic apparatus of claim 18, further comprising a color filter, a color conversion layer, a touch screen layer, a polarizing layer, or a combination thereof. 